FGF mutants with reduced proteolysis and aggregation

ABSTRACT

The invention provides FGF21 mutant polypeptides with reduced proteolysis and aggregation, pharmaceutical compositions comprising the same.

This application is a divisional of U.S. patent application Ser. No.13/327,504 filed Dec. 15, 2011, which is a divisional of U.S.application Ser. No. 13/196,544 filed Aug. 2, 2011, now U.S. Pat. No.8,410,051, which is a continuation of U.S. application Ser. No.12/455,610 filed Jun. 3, 2009, now U.S. Pat. No. 8,034,770 which claimspriority benefit of U.S. Provisional Patent Application No. 61/058,861filed Jun. 4, 2008, U.S. Provisional Patent Application No. 61/058,919filed Jun. 4, 2008, U.S. Provisional Patent Application No. 61/164,364filed Mar. 27, 2009, and U.S. Provisional Patent Application No.61/175,736 filed May 5, 2009, each of which is incorporated herein inits entirety.

REFERENCE TO THE SEQUENCE LISTING

The present application is being filed along with a Sequence Listing inelectronic format. The Sequence Listing is provided as a file entitledA-1429-US-DIV_PAmend_ST25.txt, created Dec. 19, 2011, which is 59 KB insize. The information in the electronic format of the Sequence Listingis incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to nucleic acid molecules encoding FGF21 mutantpolypeptides, FGF21 mutant polypeptides, pharmaceutical compositionscomprising FGF21 mutant polypeptides, and methods for treating metabolicdisorders using such nucleic acids, polypeptides, or pharmaceuticalcompositions.

2. Background of the Invention

FGF21 is a secreted polypeptide that belongs to a subfamily offibroblast growth factors (FGFs) that includes FGF19, FGF21, and FGF23(Itoh et al., 2004, Trend Genet. 20: 563-69). FGF21 is an atypical FGFin that it is heparin independent and functions as a hormone in theregulation of glucose, lipid, and energy metabolism.

FGF21 was isolated from a liver cDNA library as a hepatic secretedfactor. It is highly expressed in liver and pancreas and is the onlymember of the FGF family to be primarily expressed in liver. Transgenicmice overexpressing FGF21 exhibit metabolic phenotypes of slow growthrate, low plasma glucose and triglyceride levels, and an absence ofage-associated type 2 diabetes, islet hyperplasia, and obesity.Pharmacological administration of recombinant FGF21 protein in rodentand primate models results in normalized levels of plasma glucose,reduced triglyceride and cholesterol levels, and improved glucosetolerance and insulin sensitivity. In addition, FGF21 reduces bodyweight and body fat by increasing energy expenditure, physical activity,and metabolic rate. Experimental research provides support for thepharmacological administration of FGF21 for the treatment of type 2diabetes, obesity, dyslipidemia, and other metabolic conditions ordisorders in humans.

Human FGF21 has a short half-life in vivo. In mice, the half-life ofhuman FGF21 is 1 to 2 hours, and in cynomolgus monkeys, the half-life is2.5 to 3 hours. In developing an FGF21 protein for use as a therapeuticin the treatment of type 2 diabetes, an increase in half-life would bedesirable. FGF21 proteins having an enhanced half-life would allow forless frequent dosing of patients being administered the protein. Suchproteins are described herein.

SUMMARY OF THE INVENTION

The present disclosure provides an isolated polypeptide comprising anamino acid sequence of SEQ ID NO:4, further comprising the substitutionof any amino acid for: the alanine residue at position 45, the leucineresidue at position 86, the leucine residue at position 98, the alanineresidue at position 111, the alanine residue at position 129, theglycine residue at position 170, the proline residue at position 171 orthe serine residue at position 172, and combinations thereof. In oneembodiment the isolated polypeptide comprises the substitution of anyamino acid for: the leucine residue at position 98, the proline residueat 171 or both the leucine residue at position 98 and the prolineresidue at position 171. In another embodiment the isolated polypeptidecomprises the substitution of any amino acid for both the leucineresidue at position 98 and the proline residue at position 171.

The present disclosure also provides an isolated polypeptide comprisingan amino acid sequence of SEQ ID NO: 4 having: (a) at least one aminoacid substitution that is: (i) a glutamine, isoleucine, or lysineresidue at position 19; (ii) a histidine, leucine, or phenylalanineresidue at position 20; (iii) an isoleucine, phenylalanine, tyrosine, orvaline residue at position 21; (iv) an isoleucine, phenylalanine, orvaline residue at position 22; (v) an alanine or arginine residue atposition 150; (vi) an alanine or valine residue at position 151; (vii) ahistidine, leucine, phenylalanine, or valine residue at position 152;(viii) an alanine, asparagine, aspartic acid, cysteine, glutamic acid,glutamine, proline, or serine residue at position 170; (ix) an alanine,arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine,glycine, histidine, lysine, serine, threonine, tryptophan, or tyrosineresidue at position 171; (x) a leucine or threonine residue at position172; or (xi) an arginine or glutamic acid residue at position 173; and(b) at least one amino acid substitution that is: (i) an arginine,glutamic acid, or lysine residue at position 26; (ii) an arginine,glutamic acid, glutamine, lysine, or threonine residue at position 45;(iii) a threonine residue at position 52; (iv) a cysteine, glutamicacid, glycine, or serine residue at position 58; (v) an alanine,arginine, glutamic acid, or lysine residue at position 60; (vi) analanine, arginine, cysteine, or histidine residue at position 78; (vii)a cysteine or threonine residue at position 86; (viii) an alanine,arginine, glutamic acid, lysine, or serine residue at position 88; (ix)an arginine, cysteine, glutamic acid, glutamine, lysine, or threonineresidue at position 98; (x) an arginine, aspartic acid, cysteine, orglutamic acid residue at position 99; (xi) a lysine or threonine residueat position 111; (xii) an arginine, asparagine, aspartic acid, glutamicacid, glutamine, histidine, or lysine residue at position 129; or (xiii)an arginine, glutamic acid, histidine, lysine, or tyrosine residue atposition 134; and combinations thereof. In one embodiment the residue atposition 98 is arginine and the residue at position 171 is proline, andin another embodiment the polypeptide can comprise an amino acidsequence that is at least 85 percent identical to the amino acidsequence of SEQ ID NO: 4, but wherein the at least one amino acidsubstitution of (a)(i)-(xi) and (b)(i)-(xiii) is not further modified.

The present disclosure additionally provides an isolated polypeptidecomprising an amino acid sequence of SEQ ID NO: 4 having at least oneamino acid substitution that is: (a) a glutamine, lysine or isoleucineresidue at position 19; (b) a histidine, leucine, or phenylalanineresidue at position 20; (c) an isoleucine, phenylalanine, tyrosine, orvaline residue at position 21; (d) an isoleucine, phenylalanine, orvaline residue at position 22; (e) an alanine or arginine residue atposition 150; (f) an alanine or valine residue at position 151; (g) ahistidine, leucine, phenylalanine, or valine residue at position 152;(h) an alanine, aspartic acid, cysteine, or proline residue at position170; (i) an alanine, arginine, asparagine, aspartic acid, cysteine,glutamic acid, glutamine, glycine, histidine, lysine, serine, threonine,tryptophan, or tyrosine residue at position 171; (j) a leucine residueat position 172; or (k) an arginine or glutamic acid residue at position173; and combinations thereof. In one embodiment the residue at position171 is proline, and in another embodiment the polypeptide can comprisean amino acid sequence that is at least 85 percent identical to theamino acid sequence of SEQ ID NO: 4, but wherein the at least one aminoacid substitution of (a)-(k) is not further modified.

The present disclosure further provides an isolated polypeptidecomprising an amino acid sequence of SEQ ID NO: 4 having at least oneamino acid substitution that is: (a) an arginine, glutamic acid, orlysine residue at position 26; (b) an arginine, glutamic acid,glutamine, lysine, or threonine residue at position 45; (c) a threonineresidue at position 52; (d) a glutamic acid, glycine, or serine residueat position 58; (e) an alanine, arginine, glutamic acid, or lysineresidue at position 60; (f) an alanine, arginine, or histidine residueat position 78; (g) an alanine residue at position 88; (h) an arginine,glutamic acid, glutamine, lysine, or threonine residue at position 98;(i) an arginine, aspartic acid, cysteine, or glutamic acid residue atposition 99; (j) a lysine or threonine residue at position 111; (k) anarginine, asparagine, aspartic acid, glutamic acid, glutamine,histidine, or lysine residue at position 129; or (1) an arginine,glutamic acid, histidine, lysine, or tyrosine residue at position 134;and combinations thereof. In one embodiment, the residue at position 98is arginine and in another embodiment the polypeptide can comprise anamino acid sequence that is at least 85 percent identical to the aminoacid sequence of SEQ ID NO: 4, but wherein the at least one amino acidsubstitution of (a)-(l) is not further modified.

In various embodiments, the polypeptides disclosed herein can furthercomprise at least one amino acid substitution that is: (a) aphenylalanine, proline, alanine, serine or glycine at position 179; (b)a glutamic acid, glycine, proline, or serine at position 180; or (c) alysine, glycine, threonine, alanine, leucine, or proline at position 181and can further comprise 1 to 10 amino acid residues fused to theC-terminus of the polypeptide, and can be any amino acid, for example,one or more residues selected from the group consisting of glycine,proline and combinations thereof.

In various embodiments, the polypeptides disclosed herein can comprise(a) an amino-terminal truncation of no more than 8 amino acid residues,wherein the polypeptide is capable of lowering blood glucose in amammal; (b) a carboxyl-terminal truncation of no more than 12 amino acidresidues, wherein the polypeptide is capable of lowering blood glucosein a mammal; or (c) an amino-terminal truncation of no more than 8 aminoacid residues and a carboxyl-terminal truncation of no more than 12amino acid residues, wherein the polypeptide is capable of loweringblood glucose in a mammal.

In some embodiments, the polypeptides disclosed herein can be covalentlylinked to one or more polymers, such as PEG. In other embodiments, thepolypeptides of the present invention can be fused to a heterologousamino acid sequence, optionally via a linker, such as GGGGGSGGGSGGGGS(SEQ ID NO: 23). The heterologous amino acid sequence can be an IgGconstant domain or fragment thereof, such as the amino acid sequence ofSEQ ID NO:13. Such fusion polypeptides disclosed herein can also formmultimers.

The present disclosure also provides pharmaceutical compositionscomprising the polypeptides disclosed herein and a pharmaceuticallyacceptable formulation agent. Such pharmaceutical compositions can beused in a method for treating a metabolic disorder, and the methodcomprises administering to a human patient in need thereof apharmaceutical composition of the present invention. Metabolic disordersthat can be treated include diabetes and obesity.

Also provided are isolated nucleic acid molecules encoding thepolypeptides of disclosed herein, as well as vectors comprising suchnucleic acid molecules and host cells comprising such nucleic acidmolecules.

Truncated forms of the polypeptide of SEQ ID NO:4 are also disclosed. Invarious embodiments the polypeptide can comprise: (a) an amino-terminaltruncation of no more than 8 amino acid residues, wherein thepolypeptide is capable of lowering blood glucose in a mammal; (b) acarboxyl-terminal truncation of no more than 12 amino acid residues,wherein the polypeptide is capable of lowering blood glucose in amammal; or (c) an amino-terminal truncation of no more than 8 amino acidresidues and a carboxyl-terminal truncation of no more than 12 aminoacid residues, wherein the polypeptide is capable of lowering bloodglucose in a mammal.

The present disclosure additionally provides an isolated fusion proteinthat can comprise: (a) an IgG constant domain; (b) a linker sequencefused to the IgG constant domain; and (c) an FGF21 mutant fused to thelinker sequence and comprising the amino acid sequence of SEQ ID NO: 4wherein the an arginine residue has been substituted for the leucineresidue at position 98 and a glycine residue has been substituted forthe proline residue at position 171. In one embodiment, the linkersequence can comprise GGGGGSGGGSGGGGS (SEQ ID NO:23) and in another theIgG constant domain can comprise SEQ ID NO: 13. In another embodiment,the linker sequence comprises GGGGGSGGGSGGGGS (SEQ ID NO:23) and the IgGconstant domain comprises the amino acid sequence of SEQ ID NO: 13. Instill another embodiment the N terminus of the linker is fused to the Cterminus of the IgG constant domain and the N terminus of the FGF21mutant is fused to the C terminus of the linker. The disclosed fusionproteins can form multimers.

In various embodiments of the fusion protein, the FGF21 mutant componentcan comprise at least one amino acid substitution that is: (a) aphenylalanine, proline, alanine, serine or glycine at position 179; (b)a glutamic acid, glycine, proline, or serine at position 180; or (c) alysine, glycine, threonine, alanine, leucine, or proline at position 181and can further comprise 1 to 10 amino acid residues fused to theC-terminus of the FGF21 mutant, and the 1 to 10 amino acid residues, andcan be any amino acid, for example, one or more residues selected fromthe group consisting of glycine, proline and combinations thereof.

In still other embodiments of the fusion protein, the FGF21 mutantcomponent can comprise: (a) an amino-terminal truncation of no more than8 amino acid residues, wherein the polypeptide is capable of loweringblood glucose in a mammal; (b) a carboxyl-terminal truncation of no morethan 12 amino acid residues, wherein the polypeptide is capable oflowering blood glucose in a mammal; or (c) an amino-terminal truncationof no more than 8 amino acid residues and a carboxyl-terminal truncationof no more than 12 amino acid residues, wherein the polypeptide iscapable of lowering blood glucose in a mammal. In another embodiment,the FGF21 mutant component of a fusion protein can comprise an aminoacid sequence that is at least 85 percent identical to the amino acidsequence of SEQ ID NO: 4, but wherein the arginine and glycine residuesare not further modified.

The present disclosure also provides pharmaceutical compositionscomprising the fusion protein disclosed herein and a pharmaceuticallyacceptable formulation agent. Such pharmaceutical compositions can beused in a method for treating a metabolic disorder, the methodcomprising administering to a human patient in need thereof apharmaceutical composition of the present invention. Metabolic disordersthat can be treated include diabetes and obesity.

Also provided are isolated nucleic acid molecules encoding the fusionprotein disclosed herein, as well as vectors comprising such nucleicacid molecules and host cells comprising such nucleic acid molecules.

Specific embodiments of the present invention will become evident fromthe following more detailed description of certain embodiments and theclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1B show the results of an ELK-luciferase activity assayperformed on the FGF21 truncation mutants 7-181 and 8-181 (FIG. 1A) andthe FGF21 truncation mutants 1-172, 1-171, 1-169, and 1-164 (FIG. 1B);each panel shows the results obtained for a human FGF21 control.

FIG. 2 shows the results of an ELK-luciferase activity assay performedon a human FGF21 control and the FGF21 truncation mutants 3-181, 4-181,5-181, 7-181, 8-181, 1-180, 1-178, 1-177, 1-176, 1-175, 1-174, 1-173,1-172, 9-181, and 1-149.

FIG. 3 shows the blood glucose levels measured in mice injected with PBS(solid bar), human FGF21 control (open bar), or the FGF21 truncationmutants 8-181 (gray bar) and 9-181 (stippled bar).

FIG. 4 shows the percent change in blood glucose levels measured in miceinjected with PBS (solid circles), an Fc-FGF21 control (WT) (opencircles), or truncated Fc-FGF21 fusion proteins comprising amino acidresidues 5-181 (solid triangles) or 7-181 (open triangles).

FIG. 5 shows the percent change in blood glucose levels measured in miceinjected with PBS (solid circles), an FGF21-Fc control (WT) (opencircles), a truncated FGF21-Fc fusion protein comprising residues 1-175(solid triangles), or a truncated Fc-FGF21 protein comprising amino acidresidues 1-171 (open triangles).

FIGS. 6A-6D show the results of liquid chromatography-mass spectrometry(LC-MS) analysis of a human Fc(5)FGF21 control sample (FIG. 6A) andsamples of Fc(5)FGF21 drawn from mice at 6 hours (Sample D6; FIG. 6B),24 hours (Sample D24; FIG. 6C), and 48 hours (Sample D48; FIG. 6D) afterinjection.

FIGS. 7A-7D show the results if LC-MS analysis of a mammalian-derivedhuman FGF21(3)Fc control sample (FIG. 7A) and samples of FGF21(3)Fcdrawn from mice at 6 hours (Sample E6; FIG. 7B), 24 hours (Sample E24;FIG. 7C), and 48 hours (Sample E48; FIG. 7D) after injection.

FIGS. 8A-8D show the results of LC-MS analysis of an Fc(15)FGF21 controlsample (FIG. 8A) and samples of Fc(15)FGF21 drawn from mice at 6 hours(FIG. 8B), 24 hours (FIG. 8C), and 48 hours (FIG. 8D) after injection.

FIGS. 9A-9D show the results of LC-MS analysis of an FGF21(15)Fc controlsample (FIG. 9A) and samples of FGF21(15)Fc drawn from mice at 6 hours(FIG. 9B), 24 hours (FIG. 9C), and 48 hours (FIG. 9D) after injection.

FIGS. 10A-10B show the cleavage sites identified by LC-MS analysis ofFc(15)FGF21 (FIG. 10A, SEQ ID NO: 39) and FGF21(15)Fc (FIG. 10B, SEQ IDNO:25) fusion proteins injected into mice.

FIG. 11 shows the blood glucose levels measured in mice injected withPBS (solid bar), Fc(15)FGF21 (open bar), or the Fc(15)FGF21 mutantsFc(15)FGF21 G170E (gray bar), Fc(15)FGF21 P171A (stippled bar),Fc(15)FGF21 S172L (open diagonally crosshatched bar), Fc(15)FGF21G170E/P171A/S172L (solid horizontally crosshatched bar), or Fc(15)FGF21G151A (open diagonally crosshatched bar).

FIG. 12 shows the percent change in blood glucose levels measured inmice injected with PBS (solid circles), Fc(15)FGF21 (open circles), orthe Fc(15)FGF21 mutants Fc(15)FGF21 G170E (solid triangles), Fc(15)FGF21P171A (open triangles), Fc(15)FGF21 S172L (solid diamonds), Fc(15)FGF21G170E/P171A/S172L (open diamonds), or Fc(15)FGF21 G151A (solid squares).

FIG. 13 shows the blood glucose levels measured in mice injected withPBS (solid bar), Fc(15)FGF21 (open bar), or the Fc(15)FGF21 mutantsFc(15)FGF21 P150A/G151A/I152V (gray bar), Fc(15)FGF21 G170E (opendiagonally crosshatched bar), Fc(15)FGF21 G170E/P171A (gray diagonallycrosshatched bar), or Fc(15)FGF21 G170E/S172L (open diagonallycrosshatched bar).

FIG. 14 shows the percent change in blood glucose levels measured inmice injected with PBS (solid squares), Fc(15)FGF21 (open squares), orthe Fc(15)FGF21 mutants Fc(15)FGF21 P150A/G151A/I152V (solid invertedtriangles), Fc(15)FGF21 G170E (open inverted triangles), Fc(15)FGF21G170E/P171A (solid circles), or Fc(15)FGF21 G170E/S172L (open circles).

FIG. 15 shows the blood glucose levels measured in mice injected withPBS (solid bar) or the Fc(15)FGF21 mutants Fc(15)FGF21 G170E (open bar),Fc(15)FGF21 G170A (gray bar), Fc(15)FGF21 G170C (open crosshatched bar),Fc(15)FGF21 G170D (gray and white bar), Fc(15)FGF21 G170N (solidcrosshatched bar), or Fc(15)FGF21 G1705 (open crosshatched bar).

FIG. 16 shows the percent change in blood glucose levels measured inmice injected with PBS (solid circles) or the Fc(15)FGF21 mutantsFc(15)FGF21 G170E (open circles), Fc(15)FGF21 G170A (solid triangles),Fc(15)FGF21 G170C (open triangles), Fc(15)FGF21 G170D (solid diamonds),Fc(15)FGF21 G170N (open diamonds), or Fc(15)FGF21 G1705 (inverted solidtriangles).

FIG. 17 shows the blood glucose levels measured in mice injected withPBS (solid bar) or the Fc(15)FGF21 mutants Fc(15)FGF21 G170E (open bar),Fc(15)FGF21 P171E (gray bar), Fc(15)FGF21 P171H (solid crosshatchedbar), Fc(15)FGF21 P171Q (open crosshatched bar), Fc(15)FGF21 P171T(stippled bar), or Fc(15)FGF21 P171Y (gray crosshatched bar).

FIG. 18 shows the percent change in blood glucose levels measured inmice injected with PBS (solid circles) or the Fc(15)FGF21 mutantsFc(15)FGF21 G170E (open circles), Fc(15)FGF21 P171E (solid triangles),Fc(15)FGF21 P171H (open triangles), Fc(15)FGF21 P171Q (solid diamonds),Fc(15)FGF21 P171T (open diamonds), or Fc(15)FGF21 P171Y (solid squares).

FIGS. 19A-19D show the results of LC-MS analysis of an Fc(15)FGF21control sample (FIG. 19A) and samples drawn from mice at time 6 hours(FIG. 19B), 24 hours (FIG. 19C), and 48 hours (FIG. 19D) afterinjection.

FIGS. 20A-20D show the results of LC-MS analysis of an Fc(15)FGF21 G170Econtrol sample (FIG. 20A) and samples of Fc(15)FGF21 G170E drawn frommice at 6 hours (FIG. 20B), 24 hours (FIG. 20C), and 48 hours (FIG. 20D)after injection.

FIGS. 21A-21D show the results of LC-MS analysis of an Fc(15)FGF21 P171Acontrol sample (FIG. 21A) and samples of Fc(15)FGF21 P171A drawn frommice at 6 hours (FIG. 21B), 24 (FIG. 21C), and 48 hours (FIG. 21D) afterinjection.

FIGS. 22A-22D show the results of LC-MS analysis of an Fc(15)FGF21 S172Lcontrol sample (FIG. 22A) and samples of Fc(15)FGF21 S172L drawn frommice at 6 hours (FIG. 22B), 24 hours (FIG. 22C), and 48 hours (FIG. 22D)after injection.

FIGS. 23A-23D show the cleavage sites identified by LC-MS analysis ofFc(15)FGF21 (FIG. 23A, SEQ ID NO: 39), Fc(15)FGF21 G170E (FIG. 23B, SEQID NO: 40), Fc(15)FGF21 P171A (FIG. 23C, SEQ ID NO: 41), and Fc(15)FGF21S172L (FIG. 23D, SEQ ID NO: 42) fusion proteins injected in mice.

FIGS. 24A-24C show the results of an ELK-luciferase activity assayperformed on the FGF21 mutants FGF21 L99R, FGF21 L99D, and FGF21 A111T(FIG. 24A); the FGF21 mutants FGF21 A129D, FGF21 A129Q, and FGF21 A134K(FIG. 24B); and the FGF21 mutants FGF21 A134Y, FGF21 A134E, and FGF21A129K (FIG. 24C); each panel shows the results obtained for a humanFGF21 control.

FIGS. 25A-25D show the results of an ELK-luciferase activity assayperformed on the Fc-FGF21 mutants Fc-FGF21 P171G, Fc-FGF21 P171S, andFc-FGF21 P171T (FIG. 25A); the Fc-FGF21 mutants Fc-FGF21 P171Y, Fc-FGF21P171W, and Fc-FGF21 P171C (FIG. 25B); Fc(15)FGF21, Fc(15)FGF21A45K/G170E, and FGF21 A45K (FIG. 25C); and Fc(15)FGF21, Fc(15)FGF21P171E, and Fc(15)FGF21 A45K/G170E (FIG. 25D); each panel shows theresults obtained for a human FGF21 control.

FIGS. 26A-B show the aggregation as a function of time for wild typemature FGF21 and various FGF21 mutants; FIG. 26A shows the change inpercent aggregation for an FGF21 control (WT, solid diamonds) and FGF21A45K (solid circles) following incubation of 65 mg/mL protein at 4° C.for 1, 2, and 4 days, while FIG. 26B shows the change in percentaggregation for an FGF21 control (WT) and FGF21 P78C, P78R, L86T, L86R,L98C, L98R, A111T, A129D, A129Q, A129K, A134K, A134Y, and A134E (alllabeled on the plot) following incubation of 65 mg/mL protein at 4° C.for 1, 6, and 10 days.

FIG. 27 shows the results of an ELK-luciferase activity assay performedon a human FGF21 control and the FGF21 mutants FGF21 A45K, FGF21 L52T,and FGF21 L58E.

FIG. 28A is a plot show the change in aggregation levels for theFc(15)FGF21 mutants Fc(15)FGF21 6-181/G170E (solid diamonds),Fc(15)FGF21 A45K/G170E (open squares), Fc(15)FGF21 P171E (solidtriangles), Fc(15)FGF21 P171A (crosses), Fc(15)FGF21 G170E (opentriangles), and an FGF21 control (solid circles) following incubation at4° C. for 1, 4, and 8 days, and FIG. 28B is a bar graph also showing theresults of the incubation.

FIG. 29 shows the blood glucose levels measured in mice injected withPBS (vehicle) (solid circles) or the Fc(15)FGF21 mutants Fc(15)FGF21A45K/G170E (open circles), Fc(15)FGF21 A45K/P171G (solid triangles), orFc(15)FGF21 L98R/P171G (open triangles).

FIG. 30 is a plot showing the results of an ELK-luciferase activityassay performed on human FGF21 (solid circles, solid line), Fc(15)FGF21(open circles, solid line) and Fc(15)FGF21 L98R/P171G (solid triangles,dotted line).

FIG. 31 is a plot showing the percent high molecular weight aggregatesobserved after nine days at room temperature (FIG. 31A) and at 4° C.(FIG. 31B) for FGF21 (solid circles, solid line), Fc(15)FGF21 (opencircle, solid line) and Fc(15)FGF21 L98R/P171G (solid triangles, dottedline).

FIG. 32 is a series of MALDI mass spectrometry traces showing observedchanges in Fc(15)FGF21 L98R/P171G at various points over a 168 hour timeperiod.

FIG. 33 is a plot showing the percent change in blood glucose levels indb/db mice for each of a PBS vehicle control (open circles), wild-typemature FGF21 (solid squares), and the FGF21 mutants L98R, P171G(inverted solid triangles); L98R, P171G, 182P (open diamonds), and L98R,P171G, 182G (solid circles).

FIG. 34 is a plot showing the percent change in blood glucose levels inob/ob mice for each of a PBS vehicle control (solid circles), and theFGF21 mutants L98R, P171G (solid triangles); L98R, P171G, 182G, 183G(open triangles), L98R, P171G, 182G (solid diamonds) and L98R, P171G,182P (open diamonds).

FIG. 35 is a plot showing the percent change in blood glucose levels indb/db mice for each of a PBS vehicle control (open circles), and theFGF21 mutants L98R, P171G (solid squares); L98R, P171G, Y179S (opentriangles), L98R, P171G, Y179A (inverted solid triangles), L98R, P171G,180S (open diamonds) and L98R, P171G, A180G (solid circles).

FIG. 36 is a plot showing the percent change in blood glucose levelsdb/db mice for each of a PBS vehicle control (solid circles), and theFGF21 mutants L98R, P171G (open squares); L98R, P171G, Y179F (solidtriangles), and L98R, P171G, A180E (open diamonds).

FIG. 37 is a diagram graphically depicting the study design for asix-week dose escalation study performed in Rhesus monkeys; in thefigure shaded symbols indicate blood draws in the fasted state andstippled symbols indicated blood draws in the fed state.

FIGS. 38A-D is a series of plots depicting how the rhesus monkeys wererandomized on OGTT profiles, OGTT AUCs and body weight; FIG. 38A depictsbaseline glucose levels in OGTT1, solid square corresponds to group A,solid circle, solid line corresponds to group B and open circle, dashedline corresponds to group C before compounds or vehicle were assigned toeach group; FIG. 38B depicts baseline glucose levels in OGTT2, solidsquare corresponds to group A, solid circle, solid line corresponds togroup B and open circle, solid line corresponds to group C beforecompounds or vehicle were assigned to each group; FIG. 38C showsbaseline glucose levels for OGTTs 1 and 2 shown in terms of AUC, thestippled bar corresponds to group A, the shaded bar corresponds to groupB and the open bar corresponds to group C; and FIG. 38D shows baselinebody weight, the stippled bar corresponds to group A, the shaded barcorresponds to group B and the open bar corresponds to group C.

FIG. 39 is a plot showing the effects of vehicle, FGF21 and Fc-FGF21(RG)on body weight in Rhesus monkeys; shaded bars 1 and 2 correspond toweeks 1 and 2 at the low dose, open bars 3 and 4 correspond to weeks 3and 4 at the mid dose, solid bars 5 and 6 correspond to weeks 5 and 6 atthe high dose and stippled bars 7, 8 and 9 correspond to weeks 7-9during the washout period.

FIG. 40 is a plot showing the percent change in fasted insulin relativeto baseline of vehicle, FGF21 and Fc-FGF21(RG) on fasted insulin levelsin Rhesus monkeys; shaded bars 1 and 2 correspond to weeks 1 and 2 atthe low dose, open bars 3 and 4 correspond to weeks 3 and 4 at the middose, solid bars 5 and 6 correspond to weeks 5 and 6 at the high doseand stippled bars 7 and 8 correspond to weeks 7 and 8 during the washoutperiod.

FIG. 41 is a plot showing the effects of vehicle, FGF21 andFc-FGF21(RG), given at the high dose, on fed insulin levels of Rhesusmonkeys acquired during weeks 5 and 6 of the study; solid barscorrespond to week 5 and shaded bars correspond to week 6.

FIG. 42 is a plot showing the glucose profiles of OGTT5 performed at theend of the two week high-dose treatment with Fc-FGF21(RG); solid circle,solid line corresponds to vehicle, open square, dotted line correspondsto FGF21 and solid triangle, solid line corresponds to Fc-FGF21(RG).

FIG. 43 is a plot showing the insulin profiles of OGTT5 performed at theend of the two week high-dose treatment with Fc-FGF21(RG); solid circle,solid line corresponds to vehicle, open square, dotted line correspondsto FGF21 and solid triangle, solid line corresponds to Fc-FGF21(RG).

FIG. 44 is a plot showing the glucose OGTT AUC1-3 determined at the endof each dose period (low, mid and high dose) of the Rhesus monkeys; openbars correspond to AUC3 calculated from glucose measurements duringOGTT3, solid bars correspond to AUC4 calculated from glucosemeasurements during OGTT4 and shaded bars correspond to AUC5 calculatedfrom glucose measurements during OGTT5.

FIG. 45 is a graph showing the effects of vehicle, FGF21 andFc-FGF21(RG) on percent change from baseline of the fasted plasmatriglyceride levels from each group of Rhesus monkeys; shaded bars 1 and2 correspond to weeks 1 and 2 at the low dose, open bars 3 and 4correspond to weeks 3 and 4 at the mid dose, solid bars 5 and 6correspond to weeks 5 and 6 at the high dose and stippled bars 7, 8 and9 correspond to weeks 7-9 during the washout period.

FIG. 46 is a graph showing fed plasma triglyceride levels from eachgroup of the Rhesus monkeys; as measured during the fifth and sixthweeks of treatment with vehicle, FGF21 or Fc-FGF21(RG) at the high dose;shaded bars correspond to week 5 and solid bars correspond to week 6.

FIG. 47 is a plot showing individual monkey FGF21 levels measured atpre-dose, and 5, 12, 19, and 26 days, with samples acquired atapproximately 21 hours after each injection.

FIG. 48 is a plot showing individual monkey Fc-FGF21(RG) levels measuredat pre-dose, and 5, 12, 19, and 26 days, with samples acquiredapproximately 5 days after each injection.

FIG. 49 is a plot showing mean concentrations of FGF21 and Fc-FGF21(RG)levels measured from the three OGTTs performed following each of thelow, mid and high doses; shaded bars correspond to OGTT3 at the lowdose, solid bars correspond to OGTT4 at the mid dose and open barscorrespond to OGTT5 at the high dose.

DETAILED DESCRIPTION OF THE INVENTION

A human FGF21 protein having enhanced properties such as an increasedhalf-life and/or decreased aggregation can be prepared using the methodsdisclosed herein and standard molecular biology methods. Optionally, thehalf-life can be further extended by fusing an antibody, or portionthereof, to the N-terminal or C-terminal end of the wild-type FGF21sequence. It is also possible to further extend the half-life ordecrease aggregation of the wild-type FGF21 protein by introducing aminoacid substitutions into the protein. Such modified proteins are referredto herein as mutants, or FGF21 mutants, and form embodiments of thepresent invention.

Recombinant nucleic acid methods used herein, including in the Examples,are generally those set forth in Sambrook et al., Molecular Cloning: ALaboratory Manual (Cold Spring Harbor Laboratory Press, 1989) or CurrentProtocols in Molecular Biology (Ausubel et al., eds., Green PublishersInc. and Wiley and Sons 1994), both of which are incorporated herein byreference for any purpose.

1. General Definitions

The term “isolated nucleic acid molecule” refers to a nucleic acidmolecule of the invention that (1) has been separated from at leastabout 50 percent of proteins, lipids, carbohydrates, or other materialswith which it is naturally found when total nucleic acid is isolatedfrom the source cells, (2) is not linked to all or a portion of apolynucleotide to which the “isolated nucleic acid molecule” is linkedin nature, (3) is operably linked to a polynucleotide which it is notlinked to in nature, or (4) does not occur in nature as part of a largerpolynucleotide sequence. Preferably, the isolated nucleic acid moleculeof the present invention is substantially free from any othercontaminating nucleic acid molecules or other contaminants that arefound in its natural environment that would interfere with its use inpolypeptide production or its therapeutic, diagnostic, prophylactic orresearch use.

The term “vector” is used to refer to any molecule (e.g., nucleic acid,plasmid, or virus) used to transfer coding information to a host cell.

The term “expression vector” refers to a vector that is suitable fortransformation of a host cell and contains nucleic acid sequences thatdirect and/or control the expression of inserted heterologous nucleicacid sequences. Expression includes, but is not limited to, processessuch as transcription, translation, and RNA splicing, if introns arepresent.

The term “operably linked” is used herein to refer to an arrangement offlanking sequences wherein the flanking sequences so described areconfigured or assembled so as to perform their usual function. Thus, aflanking sequence operably linked to a coding sequence may be capable ofeffecting the replication, transcription and/or translation of thecoding sequence. For example, a coding sequence is operably linked to apromoter when the promoter is capable of directing transcription of thatcoding sequence. A flanking sequence need not be contiguous with thecoding sequence, so long as it functions correctly. Thus, for example,intervening untranslated yet transcribed sequences can be presentbetween a promoter sequence and the coding sequence and the promotersequence can still be considered “operably linked” to the codingsequence.

The term “host cell” is used to refer to a cell which has beentransformed, or is capable of being transformed with a nucleic acidsequence and then of expressing a selected gene of interest. The termincludes the progeny of the parent cell, whether or not the progeny isidentical in morphology or in genetic make-up to the original parent, solong as the selected gene is present.

The term “isolated polypeptide” refers to a polypeptide of the presentinvention that (1) has been separated from at least about 50 percent ofpolynucleotides, lipids, carbohydrates, or other materials with which itis naturally found when isolated from the source cell, (2) is not linked(by covalent or noncovalent interaction) to all or a portion of apolypeptide to which the “isolated polypeptide” is linked in nature, (3)is operably linked (by covalent or noncovalent interaction) to apolypeptide with which it is not linked in nature, or (4) does not occurin nature. Preferably, the isolated polypeptide is substantially freefrom any other contaminating polypeptides or other contaminants that arefound in its natural environment that would interfere with itstherapeutic, diagnostic, prophylactic or research use.

The term “naturally occurring” when used in connection with biologicalmaterials such as nucleic acid molecules, polypeptides, host cells, andthe like, refers to materials which are found in nature and are notmanipulated by man. Similarly, “non-naturally occurring” as used hereinrefers to a material that is not found in nature or that has beenstructurally modified or synthesized by man. When used in connectionwith nucleotides, the term “naturally occurring” refers to the basesadenine (A), cytosine (C), guanine (G), thymine (T), and uracil (U).When used in connection with amino acids, the term “naturally occurring”refers to the 20 amino acids alanine (A), cysteine (C), aspartic acid(D), glutamic acid (E), phenylalanine (F), glycine (G), histidine (H),isoleucine (I), lysine (K), leucine (L), methionine (M), asparagine (N),proline (P), glutamine (Q), arginine (R), serine (S), threonine (T),valine (V), tryptophan (W), and tyrosine (Y).

The term “FGF21 polypeptide” refers to a naturally-occurring wild-typepolypeptide expressed in humans. For purposes of this disclosure, theterm “FGF21 polypeptide” can be used interchangeably to refer to anyfull-length FGF21 polypeptide, e.g., SEQ ID NO:2, which consists of 209amino acid residues and which is encoded by the nucleotide sequence ofSEQ ID NO: 1; any mature form of the polypeptide, e.g., SEQ ID NO:4,which consists of 181 amino acid residues and which is encoded by thenucleotide sequence of SEQ ID NO: 3, and in which the 28 amino acidresidues at the amino-terminal end of the full-length FGF21 polypeptide(i.e., which constitute the signal peptide) have been removed, andvariants thereof.

The terms “FGF21 polypeptide mutant” and “FGF21 mutant” refer to anFGF21 polypeptide variant in which a naturally occurring FGF21 aminoacid sequence has been modified. Such modifications include, but are notlimited to, one or more amino acid substitutions, includingsubstitutions with non-naturally occurring amino acid analogs, andtruncations. Thus, FGF21 polypeptide mutants include, but are notlimited to, site-directed FGF21 mutants, truncated FGF21 polypeptides,proteolysis-resistant FGF21 mutants, aggregation-reducing FGF21 mutants,FGF21 combination mutants, and FGF21 fusion proteins, as describedherein. For the purpose of identifying the specific truncations andamino acid substitutions of the FGF21 mutants of the present invention,the numbering of the amino acid residues truncated or mutatedcorresponds to that of the mature 181-residue FGF21 polypeptide.

In other embodiments of the present invention, an FGF21 polypeptidemutant comprises an amino acid sequence that is at least about 85percent identical to the amino acid sequence of SEQ ID NO: 4, butwherein specific residues conferring a desirable property to the FGF21polypeptide mutant, e.g., proteolysis-resistance, increased half life oraggregation-reducing properties and combinations thereof, have not beenfurther modified. In other words, with the exception of residues in theFGF21 mutant sequence that have been modified in order to conferproteolysis-resistance, aggregation-reducing, or other properties, about15 percent of all other amino acid residues in the FGF21 mutant sequencecan be modified. For example, in the FGF21 mutant Q173E, up to 15percent of all amino acid residues other than the glutamic acid residue,which was substituted for glutamine at position 173, could be modified.In still other embodiments, an FGF21 polypeptide mutant comprises anamino acid sequence that is at least about 90 percent, or about 95, 96,97, 98, or 99 percent identical to the amino acid sequence of SEQ ID NO:4, but wherein the specific residues conferring the FGF21 polypeptidemutant's proteolysis-resistance or aggregation-reducing properties havenot been further modified. Such FGF21 polypeptide mutants possess atleast one activity of the wild-type FGF21 polypeptide.

The present invention also encompasses a nucleic acid molecule encodingan FGF21 polypeptide mutant comprising an amino acid sequence that is atleast about 85 percent identical to the amino acid sequence of SEQ IDNO: 4, but wherein specific residues conferring a desirable property tothe FGF21 polypeptide mutant, e.g., proteolysis-resistance, increasedhalf life or aggregation-reducing properties and combinations thereofhave not been further modified. In other words, with the exception ofnucleotides that encode residues in the FGF21 mutant sequence that havebeen modified in order to confer proteolysis-resistance,aggregation-reducing, or other properties, about 15 percent of all othernucleotides in the FGF21 mutant sequence can be modified. For example,in the FGF21 mutant Q173E, up to 15 percent of all nucleotides otherthan the nucleotides encoding the glutamic acid residue, which wassubstituted for glutamine at position 173, could be modified. Thepresent invention further encompasses a nucleic acid molecule encodingan FGF21 polypeptide mutant comprising an amino acid sequence that is atleast about 90 percent, or about 95, 96, 97, 98, or 99 percent identicalto the amino acid sequence of SEQ ID NO: 4, but wherein the specificresidues conferring the FGF21 polypeptide mutant'sproteolysis-resistance or aggregation-reducing properties have not beenfurther modified. Such FGF21 mutants possess at least one activity ofthe wild-type FGF21 polypeptide.

The present invention also encompasses a nucleic acid moleculecomprising a nucleotide sequence that is at least about 85 percentidentical to the nucleotide sequence of SEQ ID NO: 3, but wherein thenucleotides encoding amino acid residues conferring the encoded FGF21polypeptide mutant's proteolysis-resistance, aggregation-reducing orother properties have not been further modified. In other words, withthe exception of residues in the FGF21 mutant sequence that have beenmodified in order to confer proteolysis-resistance,aggregation-reducing, or other properties, about 15 percent of all otheramino acid residues in the FGF21 mutant sequence can be modified. Forexample, in the FGF21 mutant Q173E, up to 15 percent of all amino acidresidues other than the glutamic acid residue, which was substituted forglutamine at position 173, could be modified. The present inventionfurther encompasses a nucleic acid molecule comprising a nucleotidesequence that is at least about 90 percent, or about 95, 96, 97, 98, or99 percent identical to the nucleotide sequence of SEQ ID NO: 3, butwherein the nucleotides encoding amino acid residues conferring theencoded FGF21 polypeptide mutant's proteolysis-resistance oraggregation-reducing properties have not been further modified. Suchnucleic acid molecules encode FGF21 mutant polypeptides possessing atleast one activity of the wild-type FGF21 polypeptide.

The term “biologically active FGF21 polypeptide mutant” refers to anyFGF21 polypeptide mutant described herein that possesses an activity ofthe wild-type FGF21 polypeptide, such as the ability to lower bloodglucose, insulin, triglyceride, or cholesterol; reduce body weight; andimprove glucose tolerance, energy expenditure, or insulin sensitivity,regardless of the type or number of modifications that have beenintroduced into the FGF21 polypeptide mutant. FGF21 polypeptide mutantspossessing a somewhat decreased level of FGF21 activity relative to thewild-type FGF21 polypeptide can nonetheless be considered to bebiologically active FGF21 polypeptide mutants.

The terms “effective amount” and “therapeutically effective amount” eachrefer to the amount of an FGF21 polypeptide mutant used to support anobservable level of one or more biological activities of the wild-typeFGF21 polypeptide, such as the ability to lower blood glucose, insulin,triglyceride, or cholesterol levels; reduce body weight; or improveglucose tolerance, energy expenditure, or insulin sensitivity.

The term “pharmaceutically acceptable carrier” or “physiologicallyacceptable carrier” as used herein refers to one or more formulationmaterials suitable for accomplishing or enhancing the delivery of anFGF21 polypeptide mutant.

The term “antigen” refers to a molecule or a portion of a molecule thatis capable of being bound by an antibody, and additionally that iscapable of being used in an animal to produce antibodies that arecapable of binding to an epitope of that antigen. An antigen may haveone or more epitopes.

The term “native Fc” refers to molecule or sequence comprising thesequence of a non-antigen-binding fragment resulting from digestion ofwhole antibody or produced by other means, whether in monomeric ormultimeric form, and can contain the hinge region. The originalimmunoglobulin source of the native Fc is preferably of human origin andcan be any of the immunoglobulins, although IgG1 and IgG2 are preferred.Native Fc molecules are made up of monomeric polypeptides that can belinked into dimeric or multimeric forms by covalent (i.e., disulfidebonds) and noncovalent association. The number of intermoleculardisulfide bonds between monomeric subunits of native Fc molecules rangesfrom 1 to 4 depending on class (e.g., IgG, IgA, and IgE) or subclass(e.g., IgG1, IgG2, IgG3, IgA1, and IgGA2). One example of a native Fc isa disulfide-bonded dimer resulting from papain digestion of an IgG (seeEllison et al., 1982, Nucleic Acids Res. 10: 4071-9). The term “nativeFc” as used herein is generic to the monomeric, dimeric, and multimericforms. An example of an Fc polypeptide sequence is presented in SEQ IDNO:13.

The term “Fc variant” refers to a molecule or sequence that is modifiedfrom a native Fc but still comprises a binding site for the salvagereceptor, FcRn (neonatal Fc receptor). International Publication Nos. WO97/34631 and WO 96/32478 describe exemplary Fc variants, as well asinteraction with the salvage receptor, and are hereby incorporated byreference. Thus, the term “Fc variant” can comprise a molecule orsequence that is humanized from a non-human native Fc. Furthermore, anative Fc comprises regions that can be removed because they providestructural features or biological activity that are not required for thefusion molecules of the FGF21 mutants of the present invention. Thus,the term “Fc variant” comprises a molecule or sequence that lacks one ormore native Fc sites or residues, or in which one or more Fc sites orresidues has be modified, that affect or are involved in: (1) disulfidebond formation, (2) incompatibility with a selected host cell, (3)N-terminal heterogeneity upon expression in a selected host cell, (4)glycosylation, (5) interaction with complement, (6) binding to an Fcreceptor other than a salvage receptor, or (7) antibody-dependentcellular cytotoxicity (ADCC). Fc variants are described in furtherdetail hereinafter.

The term “Fc domain” encompasses native Fc and Fc variants and sequencesas defined above. As with Fc variants and native Fc molecules, the term“Fc domain” includes molecules in monomeric or multimeric form, whetherdigested from whole antibody or produced by other means. In someembodiments of the present invention, an Fc domain can be fused to FGF21or a FGF21 mutant (including a truncated form of FGF21 or a FGF21mutant) via, for example, a covalent bond between the Fc domain and theFGF21 sequence. Such fusion proteins can form multimers via theassociation of the Fc domains and both these fusion proteins and theirmultimers are an aspect of the present invention.

2. Site-Specific FGF21 Mutants

The term “site-specific FGF21 mutant” or “substituted FGF21 mutant”refers to an FGF21 mutant polypeptide having an amino acid sequence thatdiffers from the amino acid sequence of a naturally occurring FGF21polypeptide sequence, e.g., SEQ ID NOs:2 and 4 and variants thereof.Site-specific FGF21 mutants can be generated by introducing amino acidsubstitutions, either conservative or non-conservative and usingnaturally or non-naturally occurring amino acids, at particularpositions of the FGF21 polypeptide.

“Conservative amino acid substitution” can involve a substitution of anative amino acid residue (i.e., a residue found in a given position ofthe wild-type FGF21 polypeptide sequence) with a nonnative residue(i.e., a residue that is not found in a given position of the wild-typeFGF21 polypeptide sequence) such that there is little or no effect onthe polarity or charge of the amino acid residue at that position.Conservative amino acid substitutions also encompass non-naturallyoccurring amino acid residues that are typically incorporated bychemical peptide synthesis rather than by synthesis in biologicalsystems. These include peptidomimetics, and other reversed or invertedforms of amino acid moieties.

Naturally occurring residues can be divided into classes based on commonside chain properties:

(1) hydrophobic: norleucine, Met, Ala, Val, Leu, Ile;

(2) neutral hydrophilic: Cys, Ser, Thr;

(3) acidic: Asp, Glu;

(4) basic: Asn, Gln, His, Lys, Arg;

(5) residues that influence chain orientation: Gly, Pro; and

(6) aromatic: Trp, Tyr, Phe.

Conservative substitutions can involve the exchange of a member of oneof these classes for another member of the same class. Non-conservativesubstitutions can involve the exchange of a member of one of theseclasses for a member from another class.

Desired amino acid substitutions (whether conservative ornon-conservative) can be determined by those skilled in the art at thetime such substitutions are desired. An exemplary (but not limiting)list of amino acid substitutions is set forth in Table 1.

TABLE 1 Amino Acid Substitutions Original Residue ExemplarySubstitutions Ala Val, Leu, Ile Arg Lys, Gln, Asn Asn Gln Asp Glu CysSer, Ala Gln Asn Glu Asp Gly Pro, Ala His Asn, Gln, Lys, Arg Ile Leu,Val, Met, Ala, Phe Leu Ile, Val, Met, Ala, Phe Lys Arg, Gln, Asn MetLeu, Phe, Ile Phe Leu, Val, Ile, Ala, Tyr Pro Ala Ser Thr, Ala, Cys ThrSer Trp Tyr, Phe Tyr Trp, Phe, Thr, Ser Val Ile, Met, Leu, Phe, Ala3. Truncated FGF21 Polypeptides

One embodiment of the present invention is directed to truncated formsof the mature FGF21 polypeptide. This embodiment of the presentinvention arose from an effort to identify truncated FGF21 polypeptidesthat are capable of providing an activity that is similar, and in someinstances superior, to untruncated forms of the mature FGF21polypeptide.

As used herein, the term “truncated FGF21 polypeptide” refers to anFGF21 polypeptide in which amino acid residues have been removed fromthe amino-terminal (or N-terminal) end of the FGF21 polypeptide, aminoacid residues have been removed from the carboxyl-terminal (orC-terminal) end of the FGF21 polypeptide, or amino acid residues havebeen removed from both the amino-terminal and carboxyl-terminal ends ofthe FGF21 polypeptide. The various truncations disclosed herein wereprepared as described herein Examples 3 and 6.

The activity of N-terminally truncated FGF21 polypeptides andC-terminally truncated FGF21 polypeptides can be assayed using an invitro ELK-luciferase assay as described in Example 4. Specific detailsof the in vitro assays that can be used to examine the activity oftruncated FGF21 polypeptides can be found in Example 4.

The activity of the truncated FGF21 polypeptides of the presentinvention can also be assessed in an in vivo assay, such as ob/ob miceas shown in Examples 5 and 7. Generally, to assess the in vivo activityof a truncated FGF21 polypeptide, the truncated FGF21 polypeptide can beadministered to a test animal intraperitoneally. After a desiredincubation period (e.g., one hour or more), a blood sample can be drawn,and blood glucose levels can be measured. Specific details of the invivo assays that can be used to examine the activity of truncated FGF21polypeptides can be found in Examples 5 and 7.

a. N-Terminal Truncations

In some embodiments of the present invention, N-terminal truncationscomprise 1, 2, 3, 4, 5, 6, 7, or 8 amino acid residues from theN-terminal end of the mature FGF21 polypeptide. As demonstrated in, forexample, Example 5 and FIG. 3, truncated FGF21 polypeptides havingN-terminal truncations of fewer than 9 amino acid residues retain theability of the mature FGF21 polypeptide to lower blood glucose in anindividual. Accordingly, in particular embodiments, the presentinvention encompasses truncated forms of the mature FGF21 polypeptide orFGF21 polypeptide mutants having N-terminal truncations of 1, 2, 3, 4,5, 6, 7, or 8 amino acid residues.

b. C-Terminal Truncations

In some embodiments of the present invention, C-terminal truncationscomprise 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 amino acid residuesfrom the C-terminal end of the mature FGF21 polypeptide. As demonstratedin, for example, Example 4 and FIG. 1B, truncated FGF21 polypeptideshaving C-terminal truncations of fewer than 13 amino acid residuesexhibited an efficacy of at least 50% of the efficacy of wild-type FGF21in an in vitro ELK-luciferase assay, indicating that these FGF21 mutantsretain the ability of the mature FGF21 polypeptide to lower bloodglucose in an individual. Accordingly, in particular embodiments, thepresent invention encompasses truncated forms of the mature FGF21polypeptide or FGF21 polypeptide mutants having C-terminal truncationsof 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 amino acid residues.

c. N-Terminal and C-Terminal Truncations

In some embodiments of the present invention, truncated FGF21polypeptides can have a combination of N-terminal and C-terminaltruncations. Truncated FGF21 polypeptides having a combination ofN-terminal and C-terminal truncations share the activity ofcorresponding truncated FGF21 polypeptides having either the N-terminalor C-terminal truncations alone. In other words, truncated FGF21polypeptides having both N-terminal truncations of fewer than 9 aminoacid residues and C-terminal truncations of fewer than 13 amino acidresidues possess similar or greater blood glucose-lowering activity astruncated FGF21 polypeptides having N-terminal truncations of fewer than9 amino acid residues or truncated FGF21 polypeptides having C-terminaltruncations of fewer than 13 amino acid residues. Accordingly, inparticular embodiments, the present invention encompasses truncatedforms of the mature FGF21 polypeptide or FGF21 polypeptide mutantshaving both N-terminal truncations of 1, 2, 3, 4, 5, 6, 7, or 8 aminoacid residues and C-terminal truncations of 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 11, or 12 amino acid residues.

As with all FGF21 mutants of the present invention, truncated FGF21polypeptides can optionally comprise an amino-terminal methionineresidue, which can be introduced by directed mutation or as a result ofa bacterial expression process.

The truncated FGF21 polypeptides of the present invention can beprepared as described in Examples 3 and 6. Those of ordinary skill inthe art, familiar with standard molecular biology techniques, can employthat knowledge, coupled with the instant disclosure, to make and use thetruncated FGF21 polypeptides of the present invention. Standardtechniques can be used for recombinant DNA, oligonucleotide synthesis,tissue culture, and transformation (e.g., electroporation, lipofection).See, e.g., Sambrook et al., Molecular Cloning: A Laboratory Manual,supra, which is incorporated herein by reference for any purpose.Enzymatic reactions and purification techniques can be performedaccording to manufacturer's specifications, as commonly accomplished inthe art, or as described herein. Unless specific definitions areprovided, the nomenclatures utilized in connection with, and thelaboratory procedures and techniques of, analytical chemistry, syntheticorganic chemistry, and medicinal and pharmaceutical chemistry describedherein are those well known and commonly used in the art. Standardtechniques can be used for chemical syntheses; chemical analyses;pharmaceutical preparation, formulation, and delivery; and treatment ofpatients.

The truncated FGF21 polypeptides of the present invention can also befused to another entity, which can impart additional properties to thetruncated FGF21 polypeptide. In one embodiment of the present invention,a truncated FGF21 polypeptide can be fused to an Fc sequence. Suchfusion can be accomplished using known molecular biological methodsand/or the guidance provided herein. The benefits of such fusionpolypeptides, as well as methods for making such fusion polypeptides,are discussed in more detail herein.

4. Proteolysis-Resistant FGF21 Mutants

As described in Example 8, mature FGF21 was found to be undergoing invivo degradation, which was ultimately determined to arise fromproteolytic attack. The in vivo degradation of mature FGF21 was found tolead to shorter effective half-life, which can adversely affect thetherapeutic potential of a molecule. Accordingly, a directed study wasperformed to identify FGF21 mutants that exhibit a resistance toproteolysis. As a result of this investigation, the sites in the matureFGF21 polypeptide that were determined to be particularly susceptible toproteolysis include the peptide bond between the amino acid residues atpositions 4-5, 20-21, 151-152, and 171-172.

A broad but focused and directed study was performed to identifyparticular substitutions that eliminate the observed proteolytic effectwhile not affecting the activity of the protein to an unacceptabledegree. Tables 8 and 11 highlight some of the mutants that were preparedand tested. As described in, for example, Examples 13 and 14, not allFGF21 mutants exhibited an ideal profile; some mutants conferredproteolysis resistance but at the cost of compromised FGF21 activity.Other mutations retained FGF21 activity but did not confer proteolysisresistance. Several mutants, including, for example, FGF21 P171G,retained a similar level of activity as wild-type FGF21 while alsoexhibiting resistance to proteolytic degradation.

One selection criteria for identifying desirable proteolysis-resistantFGF21 mutants was that the activity of the FGF21 mutant be essentiallythe same as, or greater than, the activity of wild-type FGF21.Therefore, another embodiment of the present invention is directed toFGF21 mutants that are resistant to proteolysis and still retainactivity that is essentially the same as, or greater than, wild-typeFGF21. Although less desirable in some cases, FGF21 mutants that areresistant to proteolysis but exhibit somewhat decreased activity formanother embodiment of the present invention. In some cases it can bedesirable to maintain a degree of proteolysis, and consequently, FGF21mutants that allow some degree of proteolysis to occur also form anotherembodiment of the present invention.

As with all FGF21 mutants of the present invention, theproteolysis-resistant FGF21 mutants of the present invention can beprepared as described herein. Those of ordinary skill in the art, forexample, those familiar with standard molecular biology techniques, canemploy that knowledge, coupled with the instant disclosure, to make anduse the proteolysis-resistant FGF21 mutants of the present invention.Standard techniques can be used for recombinant DNA, oligonucleotidesynthesis, tissue culture, and transformation (e.g., electroporation,lipofection). See, e.g., Sambrook et al., Molecular Cloning: ALaboratory Manual, supra, which is incorporated herein by reference forany purpose. Enzymatic reactions and purification techniques can beperformed according to manufacturer's specifications, as commonlyaccomplished in the art, or as described herein. Unless specificdefinitions are provided, the nomenclatures utilized in connection with,and the laboratory procedures and techniques of, analytical chemistry,synthetic organic chemistry, and medicinal and pharmaceutical chemistrydescribed herein are those well known and commonly used in the art.Standard techniques can be used for chemical syntheses; chemicalanalyses; pharmaceutical preparation, formulation, and delivery; andtreatment of patients.

The proteolysis-resistant FGF21 mutants of the present invention can befused to another entity, which can impart additional properties to theproteolysis-resistant FGF21 mutant. In one embodiment of the presentinvention, a proteolysis-resistant FGF21 mutant can be fused to an IgGFc sequence, e.g., SEQ ID NO:13. Such fusion can be accomplished usingknown molecular biological methods and/or the guidance provided herein.The benefits of such fusion polypeptides, as well as methods for makingsuch fusion polypeptides, are known and are discussed in more detailherein.

5. Aggregation-Reducing FGF21 Mutants

As described in Example 15, one property of the wild-type FGF21polypeptide is its propensity to aggregate. At concentrations over about5 mg/mL, the aggregation rate is high at room temperature. As shown anddescribed herein, the aggregation rate for the wild-type FGF21polypeptide is both concentration and temperature dependent.

Aggregation can prove to be a challenge when working with wild-typeFGF21 at these concentrations, such as in the context of a therapeuticformulation. Accordingly, a directed study was performed to identifyFGF21 mutants that exhibit reduced FGF21 aggregation. The resultingFGF21 mutants were then tested for the propensity to aggregate atvarious concentrations.

A broad but focused and directed study was performed to identifyparticular substitutions that eliminate or reduce the observedaggregation effect of wild-type FGF21 while not affecting the activityof the protein to an unacceptable degree. The approach for identifyingsuitable aggregation-reducing mutants is described in Example 15. Table16 highlights some of the mutants that were prepared and tested. Asdescribed in, for example, Example 17, not all FGF21 mutants exhibitedan ideal profile. Some mutants, such as FGF21 L58E had compromised FGF21activity and were not studied further. Other mutations, such as FGF21A134E, retained FGF21 activity but did not confer reduced aggregationproperties. Several mutants, such as FGF21 L98R, retained FGF21 activityand also exhibited reduced aggregation. One mutant, FGF21 A45K,surprisingly exhibited increased FGF21 activity while also exhibitingreduced aggregation properties.

One selection criteria for identifying desirable aggregation-reducingFGF21 mutants was that the activity of the FGF21 mutant be essentiallysimilar to, or greater than, the activity of wild-type FGF21. Therefore,another embodiment of the present invention is directed to FGF21 mutantshaving reduced aggregation properties while still retaining an FGF21activity that is similar to, or greater than, wild-type FGF21. Althoughless desirable in some cases, FGF21 mutants having reduced aggregationproperties but exhibiting somewhat decreased FGF21 activity form anotherembodiment of the present invention. In some cases it may be desirableto maintain a degree of aggregation, and consequently, FGF21 mutantsthat allow some degree of aggregation to occur also form anotherembodiment of the present invention.

As with all FGF21 mutants of the present invention, theaggregation-reducing FGF21 mutants of the present invention can beprepared as described herein. Those of ordinary skill in the art,familiar with standard molecular biology techniques, can employ thatknowledge, coupled with the instant disclosure, to make and use theaggregation-reducing FGF21 mutants of the present invention. Standardtechniques can be used for recombinant DNA, oligonucleotide synthesis,tissue culture, and transformation (e.g., electroporation, lipofection).See, e.g., Sambrook et al., Molecular Cloning: A Laboratory Manual,supra, which is incorporated herein by reference for any purpose.Enzymatic reactions and purification techniques can be performedaccording to manufacturer's specifications, as commonly accomplished inthe art, or as described herein. Unless specific definitions areprovided, the nomenclatures utilized in connection with, and thelaboratory procedures and techniques of, analytical chemistry, syntheticorganic chemistry, and medicinal and pharmaceutical chemistry describedherein are those well known and commonly used in the art. Standardtechniques can be used for chemical syntheses; chemical analyses;pharmaceutical preparation, formulation, and delivery; and treatment ofpatients.

The aggregation-reducing FGF21 mutants of the present invention can befused to another entity, which can impart additional properties to theaggregation-reducing FGF21 mutant. In one embodiment of the presentinvention, an aggregation-reducing FGF21 mutant can be fused to an IgGFc sequence, e.g., SEQ ID NO:13. Such fusion can be accomplished usingknown molecular biological methods and/or the guidance provided herein.The benefits of such fusion polypeptides, as well as methods for makingsuch fusion polypeptides, are discussed in more detail herein.

6. FGF21 Combination Mutants

As described herein, the wild-type FGF21 sequence possesses severalproperties that can pose significant challenges when FGF21 is used as atherapeutic molecule. Among these challenges are the protein'ssusceptibility to degradation and its propensity for aggregation at highconcentration. After an exhaustive effort to identify FGF21 polypeptidesthat overcome each of these challenges, a directed study was performedto determine whether the amino acid substitutions conferringproteolysis-resistance and those conferring aggregation-reducingproperties could be combined in an additive or synergistic fashion in asingle polypeptide sequence while maintaining activity levels that areequal to or greater than the activity of wild-type FGF21. Thisrepresented a significant challenge, as it is known in the art that theintroduction of multiple mutations in a given polypeptide can sometimesadversely affect the expression, activity, and subsequent manufacture ofthe protein.

Surprisingly, as demonstrated in, for example, Examples 19 and 20, itwas found that the desirable properties of several FGF21 mutants couldindeed be combined in an additive or synergistic fashion to generate anFGF21 mutant having enhanced pharmaceutical properties. FGF21 mutantsthat are resistant to proteolysis, have a reduced rate of aggregation,and which still retain activity that is the same as, or greater than,wild-type FGF21, are disclosed herein.

One selection criteria for identifying desirable FGF21 combinationmutants was that the activity of the FGF21 mutant be similar to, orgreater than, the activity of wild-type FGF21. Therefore, anotherembodiment of the present invention is directed to FGF21 mutants thatare proteolysis-resistant and have reduced aggregation properties whilestill retaining an FGF21 activity that is similar to, or greater than,wild-type FGF21. Although less desirable in some cases, FGF21 mutantsthat are proteolysis-resistant and have reduced aggregation propertiesbut exhibit somewhat decreased FGF21 activity form another embodiment ofthe present invention. In some cases it may be desirable to maintain adegree of proteolysis and/or aggregation, and consequently, FGF21mutants that allow some degree of proteolysis and/or aggregation alsoform another embodiment of the present invention.

As with all FGF21 mutants of the present invention, the FGF21combination mutants of the present invention can be prepared asdescribed herein. Those of ordinary skill in the art, familiar withstandard molecular biology techniques, can employ that knowledge,coupled with the instant disclosure, to make and use the FGF21combination mutants of the present invention. Standard techniques can beused for recombinant DNA, oligonucleotide synthesis, tissue culture, andtransformation (e.g., electroporation, lipofection). See, e.g., Sambrooket al., Molecular Cloning: A Laboratory Manual, supra, which isincorporated herein by reference for any purpose. Enzymatic reactionsand purification techniques can be performed according to manufacturer'sspecifications, as commonly accomplished in the art, or as describedherein. Unless specific definitions are provided, the nomenclaturesutilized in connection with, and the laboratory procedures andtechniques of, analytical chemistry, synthetic organic chemistry, andmedicinal and pharmaceutical chemistry described herein are those wellknown and commonly used in the art. Standard techniques can be used forchemical syntheses; chemical analyses; pharmaceutical preparation,formulation, and delivery; and treatment of patients.

The FGF21 combination mutants of the present invention can be fused toanother entity, which can impart additional properties to the FGF21combination mutant. In one embodiment of the present invention, an FGF21combination mutant can be fused to an IgG Fc sequence, e.g., SEQ IDNO:13. Such fusion can be accomplished using known molecular biologicalmethods and/or the guidance provided herein. The benefits of such fusionpolypeptides, as well as methods for making such fusion polypeptides,are discussed in more detail herein.

7. FGF21 Fusion Proteins

As used herein, the term “FGF21 fusion polypeptide” or “FGF21 fusionprotein” refers to a fusion of one or more amino acid residues (such asa heterologous protein or peptide) at the N-terminus or C-terminus ofany FGF21 polypeptide mutant described herein.

Heterologous peptides and polypeptides include, but are not limited to,an epitope to allow for the detection and/or isolation of an FGF21polypeptide mutant; a transmembrane receptor protein or a portionthereof, such as an extracellular domain or a transmembrane andintracellular domain; a ligand or a portion thereof which binds to atransmembrane receptor protein; an enzyme or portion thereof which iscatalytically active; a polypeptide or peptide which promotesoligomerization, such as a leucine zipper domain; a polypeptide orpeptide which increases stability, such as an immunoglobulin constantregion; a functional or non-functional antibody, or a heavy or lightchain thereof; and a polypeptide which has an activity, such as atherapeutic activity, different from the FGF21 polypeptide mutants ofthe present invention. Also encompassed by the present invention areFGF21 mutants fused to human serum albumin (HSA).

FGF21 fusion proteins can be made by fusing heterologous sequences ateither the N-terminus or at the C-terminus of an FGF21 polypeptidemutant. As described herein, a heterologous sequence can be an aminoacid sequence or a non-amino acid-containing polymer. Heterologoussequences can be fused either directly to the FGF21 polypeptide mutantor via a linker or adapter molecule. A linker or adapter molecule can beone or more amino acid residues (or -mers), e.g., 1, 2, 3, 4, 5, 6, 7,8, or 9 residues (or -mers), preferably from 10 to 50 amino acidresidues (or -mers), e.g., 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,25, 30, 35, 40, 45, or 50 residues (or -mers), and more preferably from15 to 35 amino acid residues (or -mers). A linker or adapter moleculecan also be designed with a cleavage site for a DNA restrictionendonuclease or for a protease to allow for the separation of the fusedmoieties.

a. Fc Fusions

In one embodiment of the present invention, an FGF21 polypeptide mutantis fused to one or more domains of an Fc region of human IgG. Antibodiescomprise two functionally independent parts, a variable domain known as“Fab,” that binds an antigen, and a constant domain known as “Fc,” thatis involved in effector functions such as complement activation andattack by phagocytic cells. An Fc has a long serum half-life, whereas aFab is short-lived (Capon et al., 1989, Nature 337: 525-31). When joinedtogether with a therapeutic protein, an Fc domain can provide longerhalf-life or incorporate such functions as Fc receptor binding, proteinA binding, complement fixation, and perhaps even placental transfer(Capon et al., 1989).

In vivo pharmacokinetic analysis indicated that human FGF21 has a shorthalf-life of about 1 hour in mice due to rapid clearance and in vivodegradation. Therefore, to extend the half-life of FGF21 an Fc sequencewas fused to the N- or C-terminal end of the FGF21 polypeptide. Thefusion of an Fc region to wild type FGF21, in particularly Fc fused tothe N-terminus of wild type FGF21, did not extend the half-life asexpected, however, which led to an investigation of the proteolyticdegradation of FGF21 in vivo and the identification of FGF21 mutantsthat were resistant to such degradation. Such mutants are described in,for example, Examples 8 and 11, and exhibit longer half-lives thanwild-type FGF21. These and other FGF21 fusion proteins form embodimentsof the present invention.

Throughout the disclosure, Fc-FGF21 refers to a fusion protein in whichthe Fc sequence is fused to the N-terminus of FGF21. Similarly,throughout the disclosure, FGF21-Fc refers to a fusion protein in whichthe Fc sequence is fused to the C-terminus of FGF21.

The resulting FGF21 fusion protein can be purified, for example, by theuse of a Protein A affinity column. Peptides and proteins fused to an Fcregion have been found to exhibit a substantially greater half-life invivo than the unfused counterpart. Also, a fusion to an Fc region allowsfor dimerization/multimerization of the fusion polypeptide. The Fcregion can be a naturally occurring Fc region, or can be altered toimprove certain qualities, such as therapeutic qualities, circulationtime, or reduced aggregation.

Useful modifications of protein therapeutic agents by fusion with the“Fc” domain of an antibody are discussed in detail in InternationalPublication No. WO 00/024782, which is hereby incorporated by referencein its entirety. This document discusses linkage to a “vehicle” such aspolyethylene glycol (PEG), dextran, or an Fc region.

b. Fusion Protein Linkers

When forming the fusion proteins of the present invention, a linker can,but need not, be employed. When present, the linker's chemical structuremay not critical, since it serves primarily as a spacer. The linker canbe made up of amino acids linked together by peptide bonds. In someembodiments of the present invention, the linker is made up of from 1 to20 amino acids linked by peptide bonds, wherein the amino acids areselected from the 20 naturally occurring amino acids. In variousembodiments, the 1 to 20 amino acids are selected from the amino acidsglycine, serine, alanine, proline, asparagine, glutamine, and lysine. Insome embodiments, a linker is made up of a majority of amino acids thatare sterically unhindered, such as glycine and alanine. In someembodiments, linkers are polyglycines (such as (Gly)₄ (SEQ ID NO:29) and(Gly)₅ (SEQ ID NO:30)), polyalanines, combinations of glycine andalanine (such as poly(Gly-Ala)), or combinations of glycine and serine(such as poly(Gly-Ser)). Other suitable linkers include:(Gly)₅-Ser-(Gly)₃-Ser-(Gly)₄-Ser (SEQ ID NO:23),(Gly)₄-Ser-(Gly)₄-Ser-(Gly)₄-Ser (SEQ ID NO:31), (Gly)₃-Lys-(Gly)₄ (SEQID NO:32), (Gly)₃-Asn-Gly-Ser-(Gly)₂ (SEQ ID NO:33), (Gly)₃-Cys-(Gly)₄(SEQ ID NO:34), and Gly-Pro-Asn-Gly-Gly (SEQ ID NO:35). While a linkerof 15 amino acid residues has been found to work particularly well forFGF21 fusion proteins, the present invention contemplates linkers of anylength or composition.

The linkers described herein are exemplary, and linkers that are muchlonger and which include other residues are contemplated by the presentinvention. Non-peptide linkers are also contemplated by the presentinvention. For example, alkyl linkers such as —NH—(CH₂)_(S)—C(O)—,wherein s=2 to 20, could be used. These alkyl linkers can further besubstituted by any non-sterically hindering group, including, but notlimited to, a lower alkyl (e.g., C1-C6), lower acyl, halogen (e.g., Cl,Br), CN, NH₂, or phenyl. An exemplary non-peptide linker is apolyethylene glycol linker, wherein the linker has a molecular weight of100 to 5000 kD, for example, 100 to 500 kD.

8. Chemically-Modified FGF21 Mutants

Chemically modified forms of the FGF21 polypeptide mutants describedherein, including the truncated forms of FGF21 described herein, can beprepared by one skilled in the art, given the disclosures describedherein. Such chemically modified FGF21 mutants are altered such that thechemically modified FGF21 mutant is different from the unmodified FGF21mutant, either in the type or location of the molecules naturallyattached to the FGF21 mutant. Chemically modified FGF21 mutants caninclude molecules formed by the deletion of one or morenaturally-attached chemical groups.

In one embodiment, FGF21 polypeptide mutants of the present inventioncan be modified by the covalent attachment of one or more polymers. Forexample, the polymer selected is typically water-soluble so that theprotein to which it is attached does not precipitate in an aqueousenvironment, such as a physiological environment. Included within thescope of suitable polymers is a mixture of polymers. Preferably, fortherapeutic use of the end-product preparation, the polymer will bepharmaceutically acceptable. Non-water soluble polymers conjugated toFGF21 polypeptide mutants of the present invention also form an aspectof the invention.

Exemplary polymers each can be of any molecular weight and can bebranched or unbranched. The polymers each typically have an averagemolecular weight of between about 2 kDa to about 100 kDa (the term“about” indicating that in preparations of a water-soluble polymer, somemolecules will weigh more and some less than the stated molecularweight). The average molecular weight of each polymer is preferablybetween about 5 kDa and about 50 kDa, more preferably between about 12kDa and about 40 kDa, and most preferably between about 20 kDa and about35 kDa.

Suitable water-soluble polymers or mixtures thereof include, but are notlimited to, N-linked or O-linked carbohydrates, sugars, phosphates,polyethylene glycol (PEG) (including the forms of PEG that have beenused to derivatize proteins, including mono-(C₁-C₁₀), alkoxy-, oraryloxy-polyethylene glycol), monomethoxy-polyethylene glycol, dextran(such as low molecular weight dextran of, for example, about 6 kD),cellulose, or other carbohydrate based polymers, poly-(N-vinylpyrrolidone)polyethylene glycol, propylene glycol homopolymers,polypropylene oxide/ethylene oxide co-polymers, polyoxyethylated polyols(e.g., glycerol), and polyvinyl alcohol. Also encompassed by the presentinvention are bifunctional crosslinking molecules that can be used toprepare covalently attached FGF21 polypeptide mutant multimers. Alsoencompassed by the present invention are FGF21 mutants covalentlyattached to polysialic acid.

In some embodiments of the present invention, an FGF21 mutant iscovalently, or chemically, modified to include one or more water-solublepolymers, including, but not limited to, polyethylene glycol (PEG),polyoxyethylene glycol, or polypropylene glycol. See, e.g., U.S. Pat.Nos. 4,640,835; 4,496,689; 4,301,144; 4,670,417; 4,791,192; and4,179,337. In some embodiments of the present invention, an FGF21 mutantcomprises one or more polymers, including, but not limited to,monomethoxy-polyethylene glycol, dextran, cellulose, anothercarbohydrate-based polymer, poly-(N-vinyl pyrrolidone)-polyethyleneglycol, propylene glycol homopolymers, a polypropylene oxide/ethyleneoxide co-polymer, polyoxyethylated polyols (e.g., glycerol), polyvinylalcohol, or mixtures of such polymers.

In some embodiments of the present invention, an FGF21 mutant iscovalently-modified with PEG subunits. In some embodiments, one or morewater-soluble polymers are bonded at one or more specific positions (forexample, at the N-terminus) of the FGF21 mutant. In some embodiments,one or more water-soluble polymers are randomly attached to one or moreside chains of an FGF21 mutant. In some embodiments, PEG is used toimprove the therapeutic capacity of an FGF21 mutant. Certain suchmethods are discussed, for example, in U.S. Pat. No. 6,133,426, which ishereby incorporated by reference for any purpose.

In embodiments of the present invention wherein the polymer is PEG, thePEG group can be of any convenient molecular weight, and can be linearor branched. The average molecular weight of the PEG group willpreferably range from about 2 kD to about 100 kDa, and more preferablyfrom about 5 kDa to about 50 kDa, e.g., 10, 20, 30, 40, or 50 kDa. ThePEG groups will generally be attached to the FGF21 mutant via acylationor reductive alkylation through a reactive group on the PEG moiety(e.g., an aldehyde, amino, thiol, or ester group) to a reactive group onthe FGF21 mutant (e.g., an aldehyde, amino, or ester group).

The PEGylation of a polypeptide, including the FGF21 mutants of thepresent invention, can be specifically carried out using any of thePEGylation reactions known in the art. Such reactions are described, forexample, in the following references: Francis et al., 1992, Focus onGrowth Factors 3: 4-10; European Patent Nos. 0 154 316 and 0 401 384;and U.S. Pat. No. 4,179,337. For example, PEGylation can be carried outvia an acylation reaction or an alkylation reaction with a reactivepolyethylene glycol molecule (or an analogous reactive water-solublepolymer) as described herein. For the acylation reactions, a selectedpolymer should have a single reactive ester group. For reductivealkylation, a selected polymer should have a single reactive aldehydegroup. A reactive aldehyde is, for example, polyethylene glycolpropionaldehyde, which is water stable, or mono C₁-C₁₀ alkoxy or aryloxyderivatives thereof (see, e.g., U.S. Pat. No. 5,252,714).

In some embodiments of the present invention, a useful strategy for theattachment of the PEG group to a polypeptide involves combining, throughthe formation of a conjugate linkage in solution, a peptide and a PEGmoiety, each bearing a special functionality that is mutually reactivetoward the other. The peptides can be easily prepared with conventionalsolid phase synthesis. The peptides are “preactivated” with anappropriate functional group at a specific site. The precursors arepurified and fully characterized prior to reacting with the PEG moiety.Ligation of the peptide with PEG usually takes place in aqueous phaseand can be easily monitored by reverse phase analytical HPLC. ThePEGylated peptides can be easily purified by preparative HPLC andcharacterized by analytical HPLC, amino acid analysis and laserdesorption mass spectrometry.

Polysaccharide polymers are another type of water-soluble polymer thatcan be used for protein modification. Therefore, the FGF21 mutants ofthe present invention fused to a polysaccharide polymer form embodimentsof the present invention. Dextrans are polysaccharide polymers comprisedof individual subunits of glucose predominantly linked by alpha 1-6linkages. The dextran itself is available in many molecular weightranges, and is readily available in molecular weights from about 1 kD toabout 70 kD. Dextran is a suitable water-soluble polymer for use as avehicle by itself or in combination with another vehicle (e.g., Fc).See, e.g., International Publication No. WO 96/11953. The use of dextranconjugated to therapeutic or diagnostic immunoglobulins has beenreported. See, e.g., European Patent Publication No. 0 315 456, which ishereby incorporated by reference. The present invention also encompassesthe use of dextran of about 1 kD to about 20 kD.

In general, chemical modification can be performed under any suitablecondition used to react a protein with an activated polymer molecule.Methods for preparing chemically modified polypeptides will generallycomprise the steps of: (a) reacting the polypeptide with the activatedpolymer molecule (such as a reactive ester or aldehyde derivative of thepolymer molecule) under conditions whereby a FGF21 polypeptide mutantbecomes attached to one or more polymer molecules, and (b) obtaining thereaction products. The optimal reaction conditions will be determinedbased on known parameters and the desired result. For example, thelarger the ratio of polymer molecules to protein, the greater thepercentage of attached polymer molecule. In one embodiment of thepresent invention, chemically modified FGF21 mutants can have a singlepolymer molecule moiety at the amino-terminus (see, e.g., U.S. Pat. No.5,234,784)

In another embodiment of the present invention, FGF21 polypeptidemutants can be chemically coupled to biotin. The biotin/FGF21polypeptide mutants are then allowed to bind to avidin, resulting intetravalent avidin/biotin/FGF21 polypeptide mutants. FGF21 polypeptidemutants can also be covalently coupled to dinitrophenol (DNP) ortrinitrophenol (TNP) and the resulting conjugates precipitated withanti-DNP or anti-TNP-IgM to form decameric conjugates with a valency of10.

Generally, conditions that can be alleviated or modulated by theadministration of the present chemically modified FGF21 mutants includethose described herein for FGF21 polypeptide mutants. However, thechemically modified FGF21 mutants disclosed herein can have additionalactivities, enhanced or reduced biological activity, or othercharacteristics, such as increased or decreased half-life, as comparedto unmodified FGF21 mutants.

9. Therapeutic Compositions of FGF21 Mutants and Administration Thereof

Therapeutic compositions comprising FGF21 mutants are within the scopeof the present invention, and are specifically contemplated in light ofthe identification of several mutant FGF21 sequences exhibiting enhancedproperties. Such FGF21 mutant pharmaceutical compositions can comprise atherapeutically effective amount of an FGF21 polypeptide mutant inadmixture with a pharmaceutically or physiologically acceptableformulation agent selected for suitability with the mode ofadministration.

Acceptable formulation materials preferably are nontoxic to recipientsat the dosages and concentrations employed.

The pharmaceutical composition can contain formulation materials formodifying, maintaining, or preserving, for example, the pH, osmolarity,viscosity, clarity, color, isotonicity, odor, sterility, stability, rateof dissolution or release, adsorption, or penetration of thecomposition. Suitable formulation materials include, but are not limitedto, amino acids (such as glycine, glutamine, asparagine, arginine, orlysine), antimicrobials, antioxidants (such as ascorbic acid, sodiumsulfite, or sodium hydrogen-sulfite), buffers (such as borate,bicarbonate, Tris-HCl, citrates, phosphates, or other organic acids),bulking agents (such as mannitol or glycine), chelating agents (such asethylenediamine tetraacetic acid (EDTA)), complexing agents (such ascaffeine, polyvinylpyrrolidone, beta-cyclodextrin, orhydroxypropyl-beta-cyclodextrin), fillers, monosaccharides,disaccharides, and other carbohydrates (such as glucose, mannose, ordextrins), proteins (such as serum albumin, gelatin, orimmunoglobulins), coloring, flavoring and diluting agents, emulsifyingagents, hydrophilic polymers (such as polyvinylpyrrolidone), lowmolecular weight polypeptides, salt-forming counterions (such assodium), preservatives (such as benzalkonium chloride, benzoic acid,salicylic acid, thimerosal, phenethyl alcohol, methylparaben,propylparaben, chlorhexidine, sorbic acid, or hydrogen peroxide),solvents (such as glycerin, propylene glycol, or polyethylene glycol),sugar alcohols (such as mannitol or sorbitol), suspending agents,surfactants or wetting agents (such as pluronics; PEG; sorbitan esters;polysorbates such as polysorbate 20 or polysorbate 80; triton;tromethamine; lecithin; cholesterol or tyloxapal), stability enhancingagents (such as sucrose or sorbitol), tonicity enhancing agents (such asalkali metal halides—preferably sodium or potassium chloride—or mannitolsorbitol), delivery vehicles, diluents, excipients and/or pharmaceuticaladjuvants (see, e.g., Remington's Pharmaceutical Sciences (18th Ed., A.R. Gennaro, ed., Mack Publishing Company 1990), and subsequent editionsof the same, incorporated herein by reference for any purpose).

The optimal pharmaceutical composition will be determined by a skilledartisan depending upon, for example, the intended route ofadministration, delivery format, and desired dosage (see, e.g.,Remington's Pharmaceutical Sciences, supra). Such compositions caninfluence the physical state, stability, rate of in vivo release, andrate of in vivo clearance of the FGF21 polypeptide mutant.

The primary vehicle or carrier in a pharmaceutical composition can beeither aqueous or non-aqueous in nature. For example, a suitable vehicleor carrier for injection can be water, physiological saline solution, orartificial cerebrospinal fluid, possibly supplemented with othermaterials common in compositions for parenteral administration. Neutralbuffered saline or saline mixed with serum albumin are further exemplaryvehicles. Other exemplary pharmaceutical compositions comprise Trisbuffer of about pH 7.0-8.5, or acetate buffer of about pH 4.0-5.5, whichcan further include sorbitol or a suitable substitute. In one embodimentof the present invention, FGF21 polypeptide mutant compositions can beprepared for storage by mixing the selected composition having thedesired degree of purity with optional formulation agents (Remington'sPharmaceutical Sciences, supra) in the form of a lyophilized cake or anaqueous solution. Further, the FGF21 polypeptide mutant product can beformulated as a lyophilizate using appropriate excipients such assucrose.

The FGF21 polypeptide mutant pharmaceutical compositions can be selectedfor parenteral delivery. Alternatively, the compositions can be selectedfor inhalation or for delivery through the digestive tract, such asorally. The preparation of such pharmaceutically acceptable compositionsis within the skill of the art.

The formulation components are present in concentrations that areacceptable to the site of administration. For example, buffers are usedto maintain the composition at physiological pH or at a slightly lowerpH, typically within a pH range of from about 5 to about 8.

When parenteral administration is contemplated, the therapeuticcompositions for use in this invention can be in the form of apyrogen-free, parenterally acceptable, aqueous solution comprising thedesired FGF21 polypeptide mutant in a pharmaceutically acceptablevehicle. A particularly suitable vehicle for parenteral injection issterile distilled water in which an FGF21 polypeptide mutant isformulated as a sterile, isotonic solution, properly preserved. Yetanother preparation can involve the formulation of the desired moleculewith an agent, such as injectable microspheres, bio-erodible particles,polymeric compounds (such as polylactic acid or polyglycolic acid),beads, or liposomes, that provides for the controlled or sustainedrelease of the product which can then be delivered via a depotinjection. Hyaluronic acid can also be used, and this can have theeffect of promoting sustained duration in the circulation. Othersuitable means for the introduction of the desired molecule includeimplantable drug delivery devices.

In one embodiment, a pharmaceutical composition can be formulated forinhalation. For example, an FGF21 polypeptide mutant can be formulatedas a dry powder for inhalation. FGF21 polypeptide mutant inhalationsolutions can also be formulated with a propellant for aerosol delivery.In yet another embodiment, solutions can be nebulized. Pulmonaryadministration is further described in International Publication No. WO94/20069, which describes the pulmonary delivery of chemically modifiedproteins.

It is also contemplated that certain formulations can be administeredorally. In one embodiment of the present invention, FGF21 polypeptidemutants that are administered in this fashion can be formulated with orwithout those carriers customarily used in the compounding of soliddosage forms such as tablets and capsules. For example, a capsule can bedesigned to release the active portion of the formulation at the pointin the gastrointestinal tract when bioavailability is maximized andpre-systemic degradation is minimized. Additional agents can be includedto facilitate absorption of the FGF21 polypeptide mutant. Diluents,flavorings, low melting point waxes, vegetable oils, lubricants,suspending agents, tablet disintegrating agents, and binders can also beemployed.

Another pharmaceutical composition can involve an effective quantity ofFGF21 polypeptide mutants in a mixture with non-toxic excipients thatare suitable for the manufacture of tablets. By dissolving the tabletsin sterile water, or another appropriate vehicle, solutions can beprepared in unit-dose form. Suitable excipients include, but are notlimited to, inert diluents, such as calcium carbonate, sodium carbonateor bicarbonate, lactose, or calcium phosphate; or binding agents, suchas starch, gelatin, or acacia; or lubricating agents such as magnesiumstearate, stearic acid, or talc.

Additional FGF21 polypeptide mutant pharmaceutical compositions will beevident to those skilled in the art, including formulations involvingFGF21 polypeptide mutants in sustained- or controlled-deliveryformulations. Techniques for formulating a variety of other sustained-or controlled-delivery means, such as liposome carriers, bio-erodiblemicroparticles or porous beads and depot injections, are also known tothose skilled in the art (see, e.g., International Publication No. WO93/15722, which describes the controlled release of porous polymericmicroparticles for the delivery of pharmaceutical compositions, andWischke & Schwendeman, 2008, Int. J. Pharm. 364: 298-327, and Freiberg &Zhu, 2004, Int. J. Pharm. 282: 1-18, which discussmicrosphere/microparticle preparation and use).

Additional examples of sustained-release preparations includesemipermeable polymer matrices in the form of shaped articles, e.g.films, or microcapsules. Sustained release matrices can includepolyesters, hydrogels, polylactides (U.S. Pat. No. 3,773,919 andEuropean Patent No. 0 058 481), copolymers of L-glutamic acid and gammaethyl-L-glutamate (Sidman et al., 1983, Biopolymers 22: 547-56),poly(2-hydroxyethyl-methacrylate) (Langer et al., 1981, J. Biomed.Mater. Res. 15: 167-277 and Langer, 1982, Chem. Tech. 12: 98-105),ethylene vinyl acetate (Langer et al., supra) orpoly-D(−)-3-hydroxybutyric acid (European Patent No. 0 133 988).Sustained-release compositions can also include liposomes, which can beprepared by any of several methods known in the art. See, e.g., Epsteinet al., 1985, Proc. Natl. Acad. Sci. U.S.A. 82: 3688-92; and EuropeanPatent Nos. 0 036 676, 0 088 046, and 0 143 949.

The FGF21 polypeptide mutant pharmaceutical composition to be used forin vivo administration typically must be sterile. This can beaccomplished by filtration through sterile filtration membranes. Wherethe composition is lyophilized, sterilization using this method can beconducted either prior to, or following, lyophilization andreconstitution. The composition for parenteral administration can bestored in lyophilized form or in a solution. In addition, parenteralcompositions generally are placed into a container having a sterileaccess port, for example, an intravenous solution bag or vial having astopper pierceable by a hypodermic injection needle.

Once the pharmaceutical composition has been formulated, it can bestored in sterile vials as a solution, suspension, gel, emulsion, solid,or as a dehydrated or lyophilized powder. Such formulations can bestored either in a ready-to-use form or in a form (e.g., lyophilized)requiring reconstitution prior to administration.

In a specific embodiment, the present invention is directed to kits forproducing a single-dose administration unit. The kits can each containboth a first container having a dried protein and a second containerhaving an aqueous formulation. Also included within the scope of thisinvention are kits containing single and multi-chambered pre-filledsyringes (e.g., liquid syringes and lyosyringes).

The effective amount of an FGF21 polypeptide mutant pharmaceuticalcomposition to be employed therapeutically will depend, for example,upon the therapeutic context and objectives. One skilled in the art willappreciate that the appropriate dosage levels for treatment will thusvary depending, in part, upon the molecule delivered, the indication forwhich the FGF21 polypeptide mutant is being used, the route ofadministration, and the size (body weight, body surface, or organ size)and condition (the age and general health) of the patient. Accordingly,the clinician can titer the dosage and modify the route ofadministration to obtain the optimal therapeutic effect. A typicaldosage can range from about 0.1 μg/kg to up to about 100 mg/kg or more,depending on the factors mentioned above. In other embodiments, thedosage can range from 0.1 μg/kg up to about 100 mg/kg; or 1 μg/kg up toabout 100 mg/kg; or 5 μg/kg, 10 μg/kg, 15 μg/kg, 20 μg/kg, 25 μg/kg, 30μg/kg, 35 μg/kg, 40 μg/kg, 45 μg/kg, 50 μg/kg, 55 μg/kg, 60 μg/kg, 65μg/kg, 70 μg/kg, 75 μg/kg, up to about 100 mg/kg. In yet otherembodiments, the dosage can be 50 μg/kg, 100 μg/kg, 150 μg/kg, 200μg/kg, 250 μg/kg, 300 μg/kg, 350 μg/kg, 400 μg/kg, 450 μg/kg, 500 μg/kg,550 μg/kg, 600 μg/kg, 650 μg/kg, 700 μg/kg, 750 μg/kg, 800 μg/kg, 850μg/kg, 900 μg/kg, 950 μg/kg, 100 μg/kg, 200 μg/kg, 300 μg/kg, 400 μg/kg,500 μg/kg, 600 μg/kg, 700 μg/kg, 800 μg/kg, 900 μg/kg, 1000 μg/kg, 2000μg/kg, 3000 μg/kg, 4000 μg/kg, 5000 μg/kg, 6000 μg/kg, 7000 μg/kg, 8000μg/kg, 9000 μg/kg or 10 mg/kg.

The frequency of dosing will depend upon the pharmacokinetic parametersof the FGF21 polypeptide mutant in the formulation being used.Typically, a clinician will administer the composition until a dosage isreached that achieves the desired effect. The composition can thereforebe administered as a single dose, as two or more doses (which may or maynot contain the same amount of the desired molecule) over time, or as acontinuous infusion via an implantation device or catheter. Furtherrefinement of the appropriate dosage is routinely made by those ofordinary skill in the art and is within the ambit of tasks routinelyperformed by them. Appropriate dosages can be ascertained through use ofappropriate dose-response data.

The route of administration of the pharmaceutical composition is inaccord with known methods, e.g., orally; through injection byintravenous, intraperitoneal, intracerebral (intraparenchymal),intracerebroventricular, intramuscular, intraocular, intraarterial,intraportal, or intralesional routes; by sustained release systems(which may also be injected); or by implantation devices. Where desired,the compositions can be administered by bolus injection or continuouslyby infusion, or by implantation device.

Alternatively or additionally, the composition can be administeredlocally via implantation of a membrane, sponge, or other appropriatematerial onto which the desired molecule has been absorbed orencapsulated. Where an implantation device is used, the device can beimplanted into any suitable tissue or organ, and delivery of the desiredmolecule can be via diffusion, timed-release bolus, or continuousadministration.

10. Therapeutic Uses of FGF21 Polypeptide Mutants

FGF21 polypeptide mutants can be used to treat, diagnose, ameliorate, orprevent a number of diseases, disorders, or conditions, including, butnot limited to metabolic disorders. In one embodiment, the metabolicdisorder to be treated is diabetes, e.g., type 2 diabetes. In anotherembodiment, the metabolic disorder is obesity. Other embodiments includemetabolic conditions or disorders such as dyslipidimia; hypertension;hepatosteaotosis, such as non-alcoholic steatohepatitis (NASH);cardiovascular disease, such as atherosclerosis; and aging.

In application, a disorder or condition such as diabetes or obesity canbe treated by administering an FGF21 polypeptide mutant as describedherein to a patient in need thereof in the amount of a therapeuticallyeffective dose. The administration can be performed as described herein,such as by IV injection, intraperitoneal injection, intramuscularinjection, or orally in the form of a tablet or liquid formation. Inmost situations, a desired dosage can be determined by a clinician, asdescribed herein, and can represent a therapeutically effective dose ofthe FGF21 mutant polypeptide. It will be apparent to those of skill inthe art that a therapeutically effective dose of FGF21 mutantpolypeptide will depend, inter alia, upon the administration schedule,the unit dose of antigen administered, whether the nucleic acid moleculeor polypeptide is administered in combination with other therapeuticagents, the immune status and the health of the recipient. The term“therapeutically effective dose,” as used herein, means that amount ofFGF21 mutant polypeptide that elicits the biological or medicinalresponse in a tissue system, animal, or human being sought by aresearcher, medical doctor, or other clinician, which includesalleviation of the symptoms of the disease or disorder being treated.

11. Antibodies

Antibodies and antibody fragments that specifically bind to the FGF21mutant polypeptides of the present invention but do not specificallybind to wild-type FGF21 polypeptides are contemplated and are within thescope of the present invention. The antibodies can be polyclonal,including monospecific polyclonal; monoclonal (MAbs); recombinant;chimeric; humanized, such as complementarity-determining region(CDR)-grafted; human; single chain; and/or bispecific; as well asfragments; variants; or chemically modified molecules thereof. Antibodyfragments include those portions of the antibody that specifically bindto an epitope on an FGF21 mutant polypeptide. Examples of such fragmentsinclude Fab and F(ab′) fragments generated by enzymatic cleavage offull-length antibodies. Other binding fragments include those generatedby recombinant DNA techniques, such as the expression of recombinantplasmids containing nucleic acid sequences encoding antibody variableregions.

Polyclonal antibodies directed toward an FGF21 mutant polypeptidegenerally are produced in animals (e.g., rabbits or mice) by means ofmultiple subcutaneous or intraperitoneal injections of the FGF21 mutantpolypeptide and an adjuvant. It can be useful to conjugate an FGF21mutant polypeptide to a carrier protein that is immunogenic in thespecies to be immunized, such as keyhole limpet hemocyanin, serum,albumin, bovine thyroglobulin, or soybean trypsin inhibitor. Also,aggregating agents such as alum are used to enhance the immune response.After immunization, the animals are bled and the serum is assayed foranti-FGF21 mutant antibody titer.

Monoclonal antibodies directed toward FGF21 mutant polypeptides can beproduced using any method that provides for the production of antibodymolecules by continuous cell lines in culture. Examples of suitablemethods for preparing monoclonal antibodies include the hybridomamethods of Kohler et al., 1975, Nature 256: 495-97 and the human B-cellhybridoma method (Kozbor, 1984, J. Immunol. 133: 3001; Brodeur et al.,Monoclonal Antibody Production Techniques and Applications 51-63 (MarcelDekker, Inc., 1987). Also provided by the invention are hybridoma celllines that produce monoclonal antibodies reactive with FGF21 mutantpolypeptides.

Monoclonal antibodies of the invention can be modified for use astherapeutics. In one embodiment, the monoclonal antibody is a “chimeric”antibody in which a portion of the heavy (H) and/or light (L) chain isidentical with or homologous to a corresponding sequence in antibodiesderived from a particular species or belonging to a particular antibodyclass or subclass, while the remainder of the chain(s) is/are identicalwith or homologous to a corresponding sequence in antibodies derivedfrom another species or belonging to another antibody class or subclass.Also included are fragments of such antibodies, so long as they exhibitthe desired biological activity. See, e.g., U.S. Pat. No. 4,816,567;Morrison et al., 1985, Proc. Natl. Acad. Sci. U.S.A. 81: 6851-55.

In another embodiment, a monoclonal antibody of the invention is a“humanized” antibody. Methods for humanizing non-human antibodies arewell known in the art. See, e.g., U.S. Pat. Nos. 5,585,089 and5,693,762. Generally, a humanized antibody has one or more amino acidresidues introduced into it from a source that is non-human.Humanization can be performed, for example, using methods described inthe art (see, e.g., Jones et al., 1986, Nature 321: 522-25; Riechmann etal., 1998, Nature 332: 323-27; Verhoeyen et al., 1988, Science 239:1534-36), by substituting at least a portion of a rodentcomplementarity-determining region for the corresponding regions of ahuman antibody.

Also encompassed by the invention are human antibodies that bind theFGF21 mutant polypeptides of the present invention. Using transgenicanimals (e.g., mice) that are capable of producing a repertoire of humanantibodies in the absence of endogenous immunoglobulin production suchantibodies are produced by immunization with an FGF21 mutant antigen(i.e., having at least 6 contiguous amino acids), optionally conjugatedto a carrier. See, e.g., Jakobovits et al., 1993, Proc. Natl. Acad. Sci.U.S.A. 90: 2551-55; Jakobovits et al., 1993, Nature 362: 255-58;Bruggermann et al., 1993, Year in Immuno. 7: 33. In one method, suchtransgenic animals are produced by incapacitating the endogenous lociencoding the heavy and light immunoglobulin chains therein, andinserting loci encoding human heavy and light chain proteins into thegenome thereof. Partially modified animals, i.e., animals having lessthan the full complement of modifications, are then cross-bred to obtainan animal having all of the desired immune system modifications. Whenadministered an immunogen, these transgenic animals produce antibodieswith human (rather than, e.g., murine) amino acid sequences, includingvariable regions that are immunospecific for these antigens. See, e.g.,International Publication Nos. WO 96/33735 and WO 94/02602. Additionalmethods are described in U.S. Pat. No. 5,545,807, InternationalPublication Nos. WO 91/10741 and WO 90/04036, and in European Patent No.0 546 073. Human antibodies can also be produced by the expression ofrecombinant DNA in host cells or by expression in hybridoma cells asdescribed herein.

In an alternative embodiment, human antibodies can also be produced fromphage-display libraries (see, e.g., Hoogenboom et al., 1991, J. Mol.Biol. 227: 381; Marks et al., 1991, J. Mol. Biol. 222: 581). Theseprocesses mimic immune selection through the display of antibodyrepertoires on the surface of filamentous bacteriophage, and subsequentselection of phage by their binding to an antigen of choice. One suchtechnique is described in International Publication No. WO 99/10494,which describes the isolation of high affinity and functional agonisticantibodies for MPL- and msk-receptors using such an approach.

Chimeric, CDR grafted, and humanized antibodies are typically producedby recombinant methods. Nucleic acids encoding the antibodies areintroduced into host cells and expressed using materials and proceduresdescribed herein. In one embodiment, the antibodies are produced inmammalian host cells, such as CHO cells. Monoclonal (e.g., human)antibodies can be produced by the expression of recombinant DNA in hostcells or by expression in hybridoma cells as described herein.

The anti-FGF21 mutant antibodies of the invention can be employed in anyknown assay method, such as competitive binding assays, direct andindirect sandwich assays, and immunoprecipitation assays (see, e.g.,Sola, Monoclonal Antibodies: A Manual of Techniques 147-158 (CRC Press,Inc., 1987), incorporated herein by reference in its entirety) for thedetection and quantitation of FGF21 mutant polypeptides. The antibodieswill bind FGF21 mutant polypeptides with an affinity that is appropriatefor the assay method being employed.

For diagnostic applications, in certain embodiments, anti-FGF21 mutantantibodies can be labeled with a detectable moiety. The detectablemoiety can be any one that is capable of producing, either directly orindirectly, a detectable signal. For example, the detectable moiety canbe a radioisotope, such as ³H, ¹⁴C, ³²P, ³⁵S, ¹²⁵I, ⁹⁹Tc, ¹¹¹In, or⁶⁷Ga; a fluorescent or chemiluminescent compound, such as fluoresceinisothiocyanate, rhodamine, or luciferin; or an enzyme, such as alkalinephosphatase, β-galactosidase, or horseradish peroxidase (Bayer et al.,1990, Meth. Enz. 184: 138-63).

Competitive binding assays rely on the ability of a labeled standard(e.g., an FGF21 mutant polypeptide, or an immunologically reactiveportion thereof) to compete with the test sample analyte (e.g., an FGF21mutant polypeptide) for binding with a limited amount of anti-FGF21mutant antibody. The amount of an FGF21 mutant polypeptide in the testsample is inversely proportional to the amount of standard that becomesbound to the antibodies. To facilitate determining the amount ofstandard that becomes bound, the antibodies typically are insolubilizedbefore or after the competition, so that the standard and analyte thatare bound to the antibodies can conveniently be separated from thestandard and analyte that remain unbound.

Sandwich assays typically involve the use of two antibodies, eachcapable of binding to a different immunogenic portion, or epitope, ofthe protein to be detected and/or quantitated. In a sandwich assay, thetest sample analyte is typically bound by a first antibody that isimmobilized on a solid support, and thereafter a second antibody bindsto the analyte, thus forming an insoluble three-part complex. See, e.g.,U.S. Pat. No. 4,376,110. The second antibody can itself be labeled witha detectable moiety (direct sandwich assays) or can be measured using ananti-immunoglobulin antibody that is labeled with a detectable moiety(indirect sandwich assays). For example, one type of sandwich assay isan enzyme-linked immunosorbent assay (ELISA), in which case thedetectable moiety is an enzyme.

The anti-FGF21 mutant antibodies of the present invention are alsouseful for in vivo imaging. An antibody labeled with a detectable moietycan be administered to an animal, preferably into the bloodstream, andthe presence and location of the labeled antibody in the host assayed.The antibody can be labeled with any moiety that is detectable in ananimal, whether by nuclear magnetic resonance, radiology, or otherdetection means known in the art.

The FGF21 mutant antibodies of the invention can be used astherapeutics. These therapeutic agents are generally agonists orantagonists, in that they either enhance or reduce, respectively, atleast one of the biological activities of an FGF21 mutant polypeptide.In one embodiment, antagonist antibodies of the invention are antibodiesor binding fragments thereof which are capable of specifically bindingto an FGF21 mutant polypeptide and which are capable of inhibiting oreliminating the functional activity of an FGF21 mutant polypeptide invivo or in vitro. In some embodiments, the antagonist antibody willinhibit the functional activity of an FGF21 mutant polypeptide by atleast about 50%, and preferably by at least about 80%. In anotherembodiment, the anti-FGF21 mutant antibody is capable of interferingwith the interaction between an FGF21 mutant polypeptide and an FGFreceptor thereby inhibiting or eliminating FGF21 mutant polypeptideactivity in vitro or in vivo. Agonist and antagonist anti-FGF21 mutantantibodies are identified by screening assays that are well known in theart.

The invention also relates to a kit comprising FGF21 mutant antibodiesand other reagents useful for detecting FGF21 mutant polypeptide levelsin biological samples. Such reagents can include a detectable label,blocking serum, positive and negative control samples, and detectionreagents.

EXAMPLES

The Examples that follow are illustrative of specific embodiments of theinvention, and various uses thereof. They are set forth for explanatorypurposes only, and should not be construed as limiting the scope of theinvention in any way.

Example 1 Preparation of FGF21 Expression Constructs

A nucleic acid sequence encoding the mature FGF21 polypeptide wasobtained by polymerase chain reaction (PCR) amplification using primershaving nucleotide sequences corresponding to the 5′ and 3′ ends of themature FGF21 sequence. Table 2 lists the primers that were used toamplify the mature FGF21 sequence.

TABLE 2 PCR Primers for Preparing FGF21 Construct SEQ ID Primer SequenceNO: Sense 5′-AGGAGGAATAACATATGCATCCAATTCCAGATTCTTCTCC-3′ 5 Antisense5′-TAGTGAGCTCGAATTCTTAGGAAGCGTAGCTGG-3′ 6

The primers used to prepare the FGF21 expression construct incorporatedrestriction endonuclease sites for directional cloning of the sequenceinto a suitable expression vector (e.g., pET30 (Novagen/EMD Biosciences;San Diego, Calif.) or pAMG33 (Amgen; Thousand Oaks, Calif.)). Theexpression vector pAMG33 contains a low-copy number R-100 origin ofreplication, a modified lac promoter, and a kanamycin-resistance gene.The expression vector pET30 contains a pBR322-derived origin ofreplication, an inducible T7 promoter, and a kanamycin-resistance gene.While expression from pAMG33 was found to be higher, pET30 was found tobe a more reliable cloning vector. Thus, the majority of the constructsdescribed in the instant application were first generated in pET30 andthen screened for efficacy. Selected sequences were then transferred topAMG33 for further amplification.

The FGF21 sequence was amplified in a reaction mixture containing 40.65μL dH₂O, 5 μL PfuUltra II Reaction Buffer (10×), 1.25 μL dNTP Mix (40mM-4×10 mM), 0.1 μL Template (100 ng/mL), 1 μL Primer1 (10 μM), 1 μLPrimer2 (10 μM), and 1 μL PfuUltra II fusion HS DNA Polymerase(Stratagene; La Jolla, Calif.). Amplification reactions were performedby heating for 2 minutes at 95° C.; followed by ten cycles at 95° C. for20 seconds, 60° C. for 20 seconds (with an additional 1° C. subtractedper cycle), and 72° C. for 15 seconds/kilobase of desired product;followed by 20 cycles at 94° C. for 20 seconds, 55° C. for 20 seconds,and 72° C. for 15 seconds/kilobase of desired product; followed by 72°C. for 3 minutes. Amplification products were digested with therestriction endonucleases NdeI, DpnI, and EcoRI; ligated into a suitablevector; and then transformed into competent cells.

Example 2 Purification of FGF21 Proteins from Bacteria

In the Examples that follow, various FGF21 proteins, including thewild-type FGF21 polypeptide, truncated FGF21 polypeptides, FGF21mutants, and FGF21 fusion proteins, were expressed in a bacterialexpression system. After expression, which is described below, the FGF21proteins were purified as described in this Example, unless otherwiseindicated.

To purify the wild-type FGF21 polypeptide, truncated FGF21 polypeptides,and FGF21 mutants from bacterial inclusion bodies, double-washedinclusion bodies (DWIBs) were solubilized in a solubilization buffercontaining guanidine hydrochloride and DTT in Tris buffer at pH 8.5 andthen mixed for one hour at room temperature, and the solubilizationmixture was added to a refold buffer containing urea, arginine,cysteine, and cystamine hydrochloride at pH 9.5 and then mixed for 24hours at 5° C. (see, e.g., Clarke, 1998, Curr. Opin. Biotechnol. 9:157-63; Mannall et al., 2007, Biotechnol. Bioeng. 97: 1523-34; Rudolphet al., 1997, “Folding proteins,” Protein Function: A Practical Approach(Creighton, ed., New York, IRL Press) 57-99; and Ishibashi et al., 2005,Protein Expr. Purif. 42: 1-6).

Following solubilization and refolding, the mixture was filtered througha 0.45 micron filter. The refold pool was then concentratedapproximately 10-fold with a 10 kD molecular weight cut-off Pall Omegacassette at a transmembrane pressure (TMP) of 20 psi, and dialfilteredwith 3 column volumes of 20 mM Tris, pH 8.0 at a TMP of 20 psi.

The clarified sample was then subjected to anion exchange (AEX)chromatography using a Q Sepharose HP resin. A linear salt gradient of 0to 250 mM NaCl in 20 mM Tris was run at pH 8.0 at 5° C. Peak fractionswere analyzed by SDS-PAGE and pooled.

The AEX eluate pool was then subjected to hydrophobic interactionchromatography (HIC) using a Phenyl Sepharose HP resin. Protein waseluted using a decreasing linear gradient of 0.7 M to 0 M ammoniumsulfate at pH 8.0 and ambient temperature. Peak fractions were analyzedby SDS-PAGE (Laemmli, 1970, Nature 227: 680-85) and pooled.

The HIC pool was concentrated with a 10 kD molecular weight cut-off PallOmega 0.2 m² cassette to 7 mg/mL at a TMP of 20 psi. The concentrate wasdialfiltered with 5 column volumes of 10 mM KPO₄, 5% sorbitol, pH 8.0 ata TMP of 20 psi, and the recovered concentrate was diluted to 5 mg/mL.Finally, the solution was filtered through a Pall mini-Kleenpac 0.2 μMPosidyne membrane.

To purify FGF21 fusion proteins and FGF21 fusion mutant proteins frombacterial inclusion bodies, double-washed inclusion bodies (DWIBs) weresolubilized in a solubilization buffer containing guanidinehydrochloride and DTT in Tris buffer at pH 8.5 and then mixed for onehour at room temperature, and the solubilization mixture was added to arefold buffer containing urea, arginine, cysteine, and cystaminehydrochloride at pH 9.5 and then mixed for 24 hours at 5° C. (see, e.g.,Clarke, 1998, Curr. Opin. Biotechnol. 9: 157-63; Mannall et al., 2007,Biotechnol. Bioeng. 97: 1523-34; Rudolph et al., 1997, “Foldingproteins,” Protein Function: A Practical Approach (Creighton, ed., NewYork, IRL Press) 57-99; and Ishibashi et al., 2005, Protein Expr. Purif.42: 1-6).

Following solubilization and refolding, the mixture was dialyzed against5 volumes of 20 mM Tris, pH 8.0 using 10 kD dialysis tubing. The pH ofthe dialyzed refold was adjusted to 5.0 with 50% acetic acid, and thenclarified by centrifugation for 30 minutes at 4K.

The clarified sample was then subjected to anion exchange (AEX)chromatography using a Q Sepharose HP resin. A linear salt gradient of 0to 250 mM NaCl in 20 mM Tris was run at pH 8.0 at 5° C. Peak fractionswere analyzed by SDS-PAGE (Laemmli, 1970, Nature 227: 680-85) andpooled.

The AEX eluate pool was then subjected to hydrophobic interactionchromatography (HIC) using a Phenyl Sepharose HP resin. Protein waseluted using a decreasing linear gradient of 0.6 M to 0 M ammoniumsulfate at pH 8.0 at ambient temperature. Peak fractions were analyzedby SDS-PAGE and pooled.

Following the HIC step, the pool was then dialyzed 60 volumes of 10 mMTris, 2.2% sucrose, 3.3% sorbitol, pH 8.5. The dialyzed pool wasconcentrated to 5 mg/mL using a jumbosep. Finally, the solution wasfiltered through a Pall mini-Kleenpac 0.2 μM Posidyne membrane.

Example 3 Preparation and Expression of Truncated FGF21 Proteins

Constructs encoding the truncated FGF21 proteins listed in Table 3 wereprepared by PCR amplification of the wild-type FGF21 expression vectoras described below (the construction of the wild-type FGF21 expressionvector is described in Example 1).

TABLE 3 FGF21 Truncations Number of Amino Acid Residues ResiduesTruncated* C-terminus Truncations 1-180 1 1-179 2 1-178 3 1-177 4 1-1765 1-175 6 1-174 7 1-173 8 1-172 9 1-171 10 1-169 12 1-168 13 1-167 141-166 15 1-165 16 1-164 17 1-160 21 1-156 25 1-152 29 1-149 32 1-113 68N-terminus Truncations 2-181 1 3-181 2 4-181 3 5-181 4 6-181 5 7-181 68-181 7 9-181 8 C- and N-terminus Truncations 5-174 11 7-172 17 9-169 209-149 40 15-169  26 15-149  46 15-113  82 *relative to mature FGF21polypeptide

Truncated FGF21 protein constructs were prepared using primers havingsequences that are homologous to regions upstream and downstream of acodon (or codons) to be deleted (resulting in the truncation). Theprimers used in such amplification reactions also provided approximately15 nucleotides of overlapping sequence to allow for recircularization ofthe amplified product, namely the entire vector now having the desiredmutant.

An exemplary truncated FGF21 construct, encoding an FGF21 proteinlacking the histidine residue at position 1 of the mature FGF21 sequence(i.e., the 2-181 truncation mutant), was prepared using the primersshown in Table 4.

TABLE 4 PCR Primers for Preparing Exemplary Truncation FGF21 Mutant SEQID Primer Sequence NO: Sense5′-GGAGATATACATATGCCAATTCCAGATTCTTCTCCATTATT- 7 3′ Antisense5′-CATATGTATATCTCCTTCTTAAAGTTAAACAAAA-3′ 8

The primers shown in Table 4 allow for the deletion of the histidineresidue as shown below, wherein the upper sequence (SEQ ID NO: 10) is aportion of a mature FGF21 polypeptide comprising a N-terminalmethionine, the second sequence is the sense primer (SEQ ID NO: 7), thethird and fourth sequences (SEQ ID NOs: 11 and 12) are portions of anFGF21 expression construct, and the fifth sequence is the antisenseprimer (SEQ ID NO: 9):

MetHisProIleProAspSerSerProLeu 5′-GGAGATATACATATG---CCAATTCCAGATTCTTCTCCATTATT TTTTGTTTAACTTTAAGAAGGAGATATACATATG CATCCAATTCCAGATTCTTCTCCATTAT T AAAACAAATTGAAATTCTTCCTCTATATGTATAC GTAGGTTAAGGTCTAAGAAGAGGTAATA A AAAACAAATTGAAATTCTTCCTCTATATGTATAC-5′

Truncated FGF21 protein constructs were prepared using essentially thePCR conditions described in Example 1. Amplification products weredigested with the restriction endonuclease DpnI, and then transformedinto competent cells. The resulting clones were sequenced to confirm theabsence of polymerase-generated errors.

Truncated FGF21 proteins were expressed by transforming competent BL21(DE3) or BL21 Star (Invitrogen; Carlsbad, Calif.) cells with theconstruct encoding a particular truncated FGF21 protein. Transformantswere grown overnight with limited aeration in TB media supplemented with40 μg/mL kanamycin, were aerated the next morning, and after a shortrecovery period, were induced in 0.4 mM IPTG. FGF21 mutants wereharvested by centrifugation 18-20 hours after induction.

Example 4 In Vitro Activity of Truncated FGF21 Proteins

Experiments were performed to identify truncated FGF21 proteins thatretain wild-type FGF21 activity in an ELK-luciferase in vitro assay.Table 5 summarizes the results obtained for FGF21 proteins havingtruncations at the N-terminus, the C-terminus, or at both the N-terminusand C-terminus ELK-luciferase assays were performed using a recombinanthuman 293T kidney cell system, in which the 293T cells overexpressbeta-klotho and luciferase reporter constructs. These constructs alsocontain sequences encoding GAL4-ELK1 and SxUAS-Luc, a luciferasereporter driven by a promoter containing five tandem copies of the Gal4binding site. Beta-klotho is a co-receptor that is required by FGF21 foractivation of its FGF receptors and induction of intracellular signaltransduction, which in turn leads to Erk and ELK phosphorylation.Luciferase activity is regulated by the level of phosphorylatedErk/ELK1, and is used to indirectly monitor and quantify FGF21 activity.

ELK-luciferase assays were performed by culturing the 293T cells in thepresence of different concentrations of wild-type FGF21 or FGF21 mutantpolypeptide for 6 hours, and then assaying the cell lysates forluciferase activity. FIGS. 1A-1B show the results of an ELK-luciferaseactivity assay performed on the FGF21 truncation mutants 7-181 and 8-181(FIG. 1A) and the FGF21 truncation mutants 1-172, 1-171, 1-169, and1-164 (FIG. 1B). The luminescence obtained in ELK-luciferase assays foreach of the FGF21 truncation mutants 3-181, 4-181, 5-181, 7-181, 8-181,1-180, 1-178, 1-177, 1-176, 1-175, 1-174, 1-173, 1-172, 9-181, and 1-149is shown in FIG. 2.

FGF21 mutant polypeptides were compared with a wild-type FGF21 standardand mutants showing an efficacy of at least 50% of the efficacy ofwild-type FGF21 were considered as having not lost FGF21 activity andwere assigned a “+” in Table 5.

TABLE 5 Truncated FGF21 Proteins: in vitro Assay Amino Acid ResiduesEfficacy Activity (+/−) C-terminus Truncations 1-180  93.2% + 1-178 95.0% + 1-177 112.0% + 1-176 104.8% + 1-174 104.6% + 1-173  96.1% +1-172  97.5% + 1-171 113.0% + 1-169  84.9% + 1-167   20% − 1-166   20% −1-165   10% − N-terminus Truncations 2-181 112.5% + 3-181 130.3% + 4-181117.0% + 5-181 119.6% + 7-181  74.2% + 8-181  24.9% − 9-181  12.5% −

Collectively, the results presented in Table 5 indicate that C-terminaldeletions of 14 or more amino acid residues (i.e., a C-terminallytruncated FGF21 protein consisting of amino acid residues 1-167 andshorter proteins) eliminate the activity of FGF21. In addition, Table 5indicates that N-terminal deletions of 7 or more amino acid residues(i.e., an N-terminally truncated FGF21 protein consisting of amino acidresidues 8-181 and shorter proteins) eliminate the activity of FGF21.Not surprisingly, truncated FGF21 proteins possessing both an N-terminaltruncation of 8 to 14 residues and a C-terminal truncation of 12 or 32residues were found to lack activity in ELK-luciferase assays.

Consistent with the data presented in Table 5, truncated FGF21polypeptides having N-terminal truncations of fewer than 7 amino acidresidues constitute embodiments of the present invention. Similarly,truncated FGF21 polypeptides having C-terminal truncations of fewer than13 amino acid residues constitute embodiments of the present invention.

Example 5 In Vivo Activity of Truncated FGF21 Proteins

FGF21 possesses a number of biological activities, including the abilityto lower blood glucose, insulin, triglyceride, or cholesterol levels;reduce body weight; or improve glucose tolerance, energy expenditure, orinsulin sensitivity. Truncated FGF21 polypeptides were further analyzedfor in vivo FGF21 activity, by introducing the truncated FGF21polypeptides into insulin resistant ob/ob mice, and measuring theability of a particular truncated FGF21 polypeptide to lower bloodglucose. The truncated FGF21 polypeptide to be tested was injectedintraperitoneally into an 8 week old ob/ob mouse (Jackson Laboratory),and blood samples were obtained at various time points following asingle injection, e.g., 0, 6, 24, 72, 120, and 168 hours afterinjection. Blood glucose levels were measured with a OneTouch Glucometer(LifeScan, Inc. Milpitas, Calif.), and the results expressed as apercent change of blood glucose relative to the baseline level of bloodglucose (i.e., at time 0).

The results of one experiment are provided in FIG. 3, which shows theamount of blood glucose detected in mice injected with the FGF21truncation mutants 8-181 and 9-181. This experiment demonstrated thattruncated FGF21 fusion proteins comprising amino acid residues 8-181exhibit blood glucose lowering activity in vivo however the activity isslightly less than the activity of wild-type FGF21 at 3 and 6 hoursafter injection, but that truncated FGF21 fusion proteins comprisingamino acid residues 9-181 do not exhibit such activity. Thus, the invivo analysis of truncated FGF21 polypeptides indicated that thedeletion of up to 7 amino acids from the N-terminus of mature FGF21 doesnot abolish the molecule's biological activity (in contrast with the invitro analysis, which suggested that the deletion of 7 amino acids fromthe N-terminus of mature FGF21 would abolish activity).

The differing results obtained with particular N-terminally truncatedFGF21 polypeptides (e.g., FGF21 8-181) in in vitro and in vivo assayscan be explained by the interaction of FGF21 with beta-klotho and FGFreceptor in effecting signal transduction. In particular, FGF21activates a dual receptor complex comprising the co-receptor beta-klothoand FGF receptor (FGFR), which initiates a signaling cascade involvingtyrosine kinase. The N-terminus of FGF21 has been shown involved inbinding and activation of FGFR while the C-terminus of FGF21 is requiredfor beta-klotho interaction (Yie et al., 2009 FEBS Lett. 583:19-24). TheELK-luciferase in vitro assay is performed in 293 kidney cells in whichthe co-receptor beta-klotho is overexpressed and FGFR is expressed atnormal levels. The amount of FGFR is low in relative to that ofbeta-klotho and the ratio of beta-klotho to FGFR in 293 cells istherefore non-physiological, which may affect receptor complex formationand ultimately ligand binding and activation of FGFR. The 293 in vitrosystem appears to be more vulnerable to N-terminally truncated FGF21polypeptides and therefore may have produced loss of activity resultsfor a few of the N-terminally truncated mutants tested, such as FGF218-181. Thus, in determining whether a particular N-terminally truncatedFGF21 mutant retained wild-type FGF21 activity, the activity of thatFGF21 mutant in the in vivo assay was considered to be dispositive.Accordingly, truncated FGF21 polypeptides having N-terminal truncationsof fewer than 8 amino acid residues are encompassed by the invention.

Example 6 Preparation and Expression of Truncated FGF21 Fusion Proteins

Because the half-life of a protein can be increased by fusing theprotein to an Fc sequence, fusion proteins comprising truncated FGF21polypeptides were prepared and analyzed. The truncated FGF21 fusionproteins listed in Table 6 were prepared from amplified FGF21 sequencesby SOEing (gene splicing by overlap extension) PCR. FGF21 fusionproteins were prepared such that the Fc portion of the humanimmunoglobulin IgG1 gene (SEQ ID NO: 13) was fused to either theN-terminus or the C-terminus of the FGF21 protein.

TABLE 6 Truncated FGF21 Fusion Proteins Amino Acid Residues Fc PositionLinker C-terminus Truncations 1-178 —NH₂ 15 1-175 —NH₂ 14 1-175 —COOH 151-171 —NH₂ 15 1-171 —COOH 15 1-170 —COOH 15 N-terminus Truncations 5-181—NH₂ 15 5-181 —COOH 15 7-181 —NH₂ 15 7-181 —COOH 15 C- and N-terminusTruncations 5-175 —NH₂ 15 5-175 —COOH 15 5-171 —NH₂ 15 5-171 —COOH 156-170 —COOH 15 7-178 —COOH 35 7-175 —NH₂ 15 7-175 —COOH 15 7-174 —COOH35 7-172 —COOH 35 7-171 —NH₂ 15 7-171 —COOH 35 7-171 —COOH 15

In particular, FGF21 fusion protein constructs (including those encodingtruncated FGF21 fusion proteins) were prepared in a series of threeamplification reactions using essentially the reaction conditionsdescribed in Example 1. In the first reaction, a pair of primers wasdesigned to produce a sequence containing an NdeI cloning site, Fcregion, and linker sequence. In the second reaction, a pair of primerswas designed to produce a sequence containing an overlapping portion ofthe linker, a portion of the FGF21 coding sequence, and an EcoRI cloningsite. Finally, in the third reaction, a pair of primers was designed forthe purpose of linking the products of the first two reactions. Anexemplary set of primers for the construction of Fc-FGF21 1-181 islisted in Table 7.

TABLE 7 PCR Primers for Preparing Exemplary FGF21 FusionProtein Construct SEQ ID Primer Sequence NO: Reaction 1 Sense5′-AGGAGGAATAACATATGGACAAAACTCACACATG-3′ 14 Antisense5′-GGATCCACCACCACCGCTACCAC-3′ 15 Reaction 2 Sense5′-GGTGGTGGTGGATCCCATCCAATTCCAGATTCTTCTCCA-3′ 16 Antisense5′-TAGTGAGCTCGAATTCTTAGGAAGCGTAGCTGG-3′ 17 Reaction 3   Sense5′-AGGAGGAATAACATATGGACAAAACTCACACATG-3′ 14 Antisense5′-TAGTGAGCTCGAATTCTTAGGAAGCGTAGCTGG-3′ 17

The product of the final reaction was digested with the restrictionendonucleases NdeI and EcoRI, ligated into the pET30 vector, and thentransformed into competent cells. The resulting clones were sequenced toconfirm the absence of polymerase-generated errors.

Example 7 In Vivo Activity of Truncated FGF21 Fusion Proteins

Fusion proteins comprising a truncated FGF21 sequence fused to an Fcsequence were generated and assayed for in vivo activity. TruncatedFGF21 fusion proteins were prepared by fusing an IgG1 Fc molecule toeither the N-terminal or C-terminal end of a truncated FGF21 protein toform a single contiguous sequence. To distinguish between N-terminal andC-terminal fusions, FGF21 fusion proteins in which the Fc molecule wasfused to the N-terminal end of the FGF21 protein are designated asFc-FGF21, and fusion proteins in which the Fc molecule was fused to theC-terminal end of the FGF21 protein are designated as FGF21-Fc.

FGF21 possesses a number of biological activities, including the abilityto lower blood glucose, insulin, triglyceride, or cholesterol levels;reduce body weight; or improve glucose tolerance, energy expenditure, orinsulin sensitivity. To assess in vivo FGF21 activity, FGF21polypeptides, FGF21 mutant polypeptides, and FGF21 fusion polypeptideswere introduced into insulin resistant ob/ob mice, and the ability of aparticular FGF21 protein to lower blood glucose levels was measured. TheFGF21 polypeptide, FGF21 mutant polypeptide, or FGF21 fusion polypeptideto be tested was injected intraperitoneally into 8 week old ob/ob mice(Jackson Laboratory), and blood samples were obtained at various timepoints following a single injection, e.g., 0, 6, 24, 72, 120, and 168hours after injection. Blood glucose levels were measured with aOneTouch Glucometer (LifeScan, Inc. Milpitas, Calif.), and the resultsexpressed as a percent change of blood glucose relative to the baselinelevel of blood glucose (i.e., at time 0).

The results of one experiment are provided in FIG. 4, which shows thepercent change in blood glucose levels observed in mice injected with aPBS control, a wild-type Fc-FGF21 control comprising amino acid residues1-181, or truncated Fc-FGF21 fusion proteins comprising amino acidresidues 5-181 or 7-181. This experiment demonstrated that truncatedFc-FGF21 fusion proteins comprising amino acid residues 5-181 or 7-181exhibit blood glucose lowering activity that is similar to the activityof wild-type Fc-FGF21 at 6 hours after injection. Thus, the in vivoanalysis of truncated FGF21 polypeptides indicated that the deletion ofup to 6 amino acids from the N-terminus of mature FGF21 does not affectthe molecule's biological activity. In vivo analysis also indicated,however, that the ability of truncated FGF21 polypeptides to lower bloodglucose was reduced and that blood glucose levels returned to baselineat 24 hours after injection (similar results were obtained withwild-type FGF21). The short in vivo activity was found to be a result ofthe proteolytic degradation of FGF21, as described in Example 8.

The results of another experiment are provided in FIG. 5, which showsthe percent change in blood glucose levels observed in mice injectedwith a PBS control, a wild-type FGF21-Fc control comprising amino acidresidues 1-181, a truncated FGF21-Fc fusion protein comprising residues1-175, or a truncated Fc-FGF21 protein comprising amino acid residues1-171. This experiment demonstrates that the wild-type FGF21-Fccomprising amino acid residues 1-181 has a sustained glucose-loweringactivity resulting in a reduction of blood glucose levels ofapproximately 30% over the time period of 24 hours to 120 hoursfollowing injection. The truncated Fc-FGF21 protein comprising aminoacid residues 1-171 exhibits delayed blood glucose lowering activityevident only at 72 hours after injection. However, the activity observedis the same as the activity of wild-type FGF21-Fc. The truncatedFGF21-Fc fusion protein comprising residues 1-175 is not active in vivoin lowering blood glucose.

Collectively, the truncation experiments described herein demonstratethat truncated FGF21 fusion proteins having an N-terminal truncationexhibit blood glucose lowering activity that is similar to that of thewild-type FGF21 fusion protein, and further, that truncated FGF21 fusionproteins in which the Fc molecule has been fused to the N-terminal endof the truncated FGF21 protein exhibit more activity than fusionproteins in which the Fc molecule has been fused to the C-terminal endof the truncated FGF21 protein.

Example 8 Observed In Vivo Degradation of FGF21

FGF21 degradation was first observed with FGF21 Fc fusion proteinconstructs as described in Example 7. In vivo pharmacokinetic analysisindicated that human FGF21 has a short half-life of about 1 hour in micedue to rapid clearance and in vivo degradation. Therefore, to extend thehalf-life of FGF21 an Fc sequence was fused to the N- or C-terminal endof the FGF21 polypeptide. However, the fusion of an Fc region did notcompletely resolve the half-life issue since fusion proteins in which anFc sequence was fused to the N- or C-terminal end of the FGF21polypeptide (and in particular Fc-FGF21 fusions, i.e., in which the Fcsequence is fused to the N-terminus of mature FGF21), did not exhibitthe expected in vivo efficacy, and instead were found to maintain bloodglucose lowering activity for no more than 24 hours in ob/ob mice. Asdescribed in FIG. 4, Fc-FGF21 fusion proteins reduced blood glucoselevels by about 30-40% at 6 hours after injection, while the bloodglucose levels returned to baseline levels at 24 hours.

The proteolytic degradation of wild-type FGF21 was subsequentlyinvestigated, and the rapid loss of in vivo activity with Fc-FGF21fusion proteins was found to be the result of in vivo degradation ofFGF21. Proteolytic degradation leads to decreased biological activity ofthe molecule in vivo and thus a shorter effective half-life, and suchdegradation adversely impacts the therapeutic use of that molecule.Accordingly, the observed degradation of FGF21 Fc fusion proteins led tothe investigation of the proteolytic degradation of FGF21 in vivo and toidentify FGF21 mutants that were resistant to such degradation.

To determine the sites of degradation, LC-MS analysis and Edmansequencing was performed on wild-type human FGF21 and FGF21 Fc fusionproteins obtained at various time points after injection into male C57B6mice. The Edman sequencing helped confirm whether the N-terminal orC-terminal end of the protein was undergoing degradation. When an Fcsequence was fused to the N-terminus of human FGF21, degradation wasfound to occur at the peptide bond between amino acid residues 151 and152 and between amino acid residues 171 and 172 of the human FGF21portion of the fusion molecule (the residue numbering above is based onthe mature FGF21 sequence and does not include the Fc portion of thefusion protein). The degradation at 171-172 was found to occur first,and was followed by degradation at 151-152. Degradation at 171-172appears to be the rate-limiting step and plays a role in the half-lifeof the molecule. When an Fc sequence was fused to the C-terminus ofFGF21, degradation was found to occur at the peptide bond between aminoacid residues 4 and 5 and between amino acid residues 20 and 21. As aresult of these experiments, it was determined that the Fc sequenceappears to protect the portion of the FGF21 sequence that is adjacent tothe Fc sequence from degradation. An analysis of the in vivo degradationof wild-type FGF21 and Fc-FGF21 fusion proteins was further conducted incynomolgus monkeys. These studies confirmed that the cleavage site ofFGF21 at amino acid residues 171-172 is the major site of degradation inmonkeys and that this site of degradation is conserved between murineand primate.

Example 9 Identification of FGF21 Proteolysis-Resistant Mutants

Suitable FGF21 mutants were identified by experimentally determining thepositions of the wild-type FGF21 sequence that are sites of majorproteolytic activity, and specific amino acid substitutions wereintroduced at these sites. Amino acid substitutions were based on FGF21sequence conservation with other species (as described in Example 8) andbiochemical conservation with other amino acid residues. A list of aminoacid substitutions that were or can be introduced into the wild-typeFGF21 protein is provided in Table 8, although Table 8 is only exemplaryand other substitutions can be made. The numbers of the positions givenin Table 8 correspond to the residue position in the mature FGF21protein, which consists of 181 amino acid residues.

TABLE 8 FGF21 Residues Mutated Amino Acid Native Position ResidueMutations 19 Arg Gln, Ile, Lys 20 Tyr His, Leu, Phe 21 Leu Ile, Phe,Tyr, Val 22 Tyr Ile, Phe, Val 150 Pro Ala, Arg 151 Gly Ala, Val 152 IleHis, Leu, Phe, Val 170 Gly Ala, Asn, Asp, Cys, Gln, Glu, Pro, Ser 171Pro Ala, Arg, Asn, Asp, Cys, Glu, Gln, Gly, His, Lys, Ser, Thr, Trp, Tyr172 Ser Leu, Thr 173 Gln Arg, Glu

Example 10 In Vivo Analysis of Fc-FGF21 and FGF21-Fc Degradation

The stability of FGF21 Fc fusion proteins in vivo was determined byinjecting mice with a fusion protein, drawing blood from the mice atvarious time points, and analyzing the serum by liquidchromatography-mass spectrometry (LC-MS). In particular, mice wereintraperitoneally injected with 10 mg/kg of Fc(5)FGF21 (expressed in E.coli and purified as described in Example 2) or FGF21(3)Fc (expressed inmammalian cells and purified according to standard procedures). Bloodwas drawn from the mice at 6, 24, and 48 hours after injection (Table 9)and collected into EDTA tubes pretreated with protease inhibitorcocktails (Roche Diagnostics). Plasma was separated by centrifuging thesamples at 12,000 g for 10 minutes. FGF21 proteins were affinitypurified from blood using an anti-human-Fc agarose resin.

TABLE 9 FGF21 Samples Sample Protein Administered Blood Withdrawn D6Fc-FGF21  6 hours D24 Fc-FGF21 24 hours D48 Fc-FGF21 48 hours E6FGF21-Fc  6 hours E24 FGF21-Fc 24 hours E48 FGF21-Fc 48 hours

Prior to analyzing the affinity purified samples by LC-MS, Fc-FGF21 andFGF21-Fc protein standards were analyzed as a reference. Proteinstandards were either reduced with tris[2-carboxyethyl]phosphine (TCEP)or not reduced. Reduced and non-reduced standards were analyzed by LC-MSusing an ACE cyano 0.3 mm×30 cm column with the column effluent sprayinginto an LCQ Classic ion-trap mass spectrometer. Since the deconvolutedspectra of the reduced samples were cleaner, the affinity purifiedsamples were reduced prior to LC-MS analysis.

The observed masses for the reduced Fc(5)FGF21 standard and samples D6,D24, and D48 are shown in FIGS. 6A-6D. The observed masses for thereduced FGF21(3)Fc standard and samples E6, E24, and E48 are shown inFIGS. 7A-7D. Some of the standard and sample eluates were subjected toEdman sequencing in order to confirm the N-terminus of the proteins andthe fragments as determined by LC-MS. Results of the LC-MS analysis ofthe standards and samples are provided in Table 10.

TABLE 10 Results of LC-MS Analysis and Predicted Fragments Intact FGF21Sample Major Observed Masses Fragment N-terminus? Fc(5)FGF21 45,339 Da 1-414 Yes standard D6 45,338 Da  1-414 Yes 44,317 Da  1-404 D24 44,321Da  1-404 Yes D48 44,327 Da  1-404 Yes 42,356 Da ? FGF21(3)Fc 46,408 Da(glycosylated, G0F)  1-410 Yes standard 44,964 Da (non-glycosylated) 1-410 E6 45,963 Da (glycosylated, G0F)  5-410 No 44,516 Da(non-glycoylated)  5-410 E24 45,963 Da (glycosylated, G0F)  5-410 No44,526 Da (non-glycosylated)  5-410 44,130 Da (glycosylated, G0F) 21-410E48 45,984 Da  5-410? No 44,130 Da 21-410 44,022 Da ?

As indicated in Table 10, all of the affinity purified samples showedsome degree of degradation after only 6 hours of circulation. After 24hours of circulation, the major product of Fc-FGF21 was a fragmentconsisting of amino acid residues 1-404, which was seen in both the Dand E samples. In the E samples, however, the major product of FGF21-Fcwas a fragment consisting of amino acid residues 5-410. For both of thefusion proteins tested, the FGF21 portion of the fusion protein was moresusceptible to degradation than the Fc portion of the protein.

Example 11 Preparation and Expression of Proteolysis-Resistant FGF21Mutants and Fusion Proteins

Constructs encoding the FGF21 mutants listed in Table 11 were preparedby PCR amplification of the wild-type FGF21 expression vector asdescribed below (the construction of the wild-type FGF21 expressionvector is described in Example 1). The goal of these experiments was togenerate FGF21 mutants that are resistant to proteolysis and exhibitlonger half-lives.

TABLE 11 Proteolysis-Resistant FGF21 Mutants Mutation(s) Fc Linker R19IR19I —COOH 15 R19K R19K —COOH 15 R19Q R19Q —COOH 15 R19K, Y20H R19K,Y20H —COOH 15 R19K, L21I R19K, L21I —COOH 15 R19K, Y20H, L21I R19K,Y20H, L21I —COOH 15 Y20F Y20F —COOH 15 Y20H Y20H —COOH 15 Y20L Y20L—COOH 15 Y20H, L21I Y20H, L21I —COOH 15 L21I L21I —COOH 15 L21F L21F—COOH 15 L21V L21V —COOH 15 L21Y L21Y —COOH 15 Y22F Y22F —COOH 15 Y22IY22I —COOH 15 Y22V Y22V —COOH 15 P150A P150A —NH₂ 15 P150R —NH₂ 15P150A, G151A P150A, G151A —NH₂ 15 P150A, I152V P150A, I152V —NH₂ 15P150A, G151A, I152V P150A, G151A, I152V —NH₂ 15 G151A G151A —NH₂ 15G151V G151V —NH₂ 15 G151A, I152V G151A, I152V —NH₂ 15 I152F I152F —NH₂15 I152H I152H —NH₂ 15 I152L I152L —NH₂ 15 I152V G170A G170A —NH₂ 15G170C G170C —NH₂ 15 G170D G170D —NH₂ 15 G170E G170E —NH₂ 15 G170N G170N—NH₂ 15 G170P G170P —NH₂ 15 G170Q G170Q —NH₂ 15 G170S G170S —NH₂ 15G170E, P171A G170E, P171A —NH₂ 15 G170E, S172L G170E, S172L —NH₂ 15G170E, P171A, S172L G170E, P171A, S172L —NH₂ 15 P171A P171A —NH₂ 15P171C —NH₂ 15 P171D —NH₂ 15 P171E —NH₂ 15 P171G —NH₂ 15 P171H —NH₂ 15P171K —NH₂ 15 P171N —NH₂ 15 P171Q —NH₂ 15 P171S —NH₂ 15 P171T —NH₂ 15P171W —NH₂ 15 P171Y —NH₂ 15 P171A, S172L P171A, S172L —NH₂ 15 S172L —NH₂15 S172T S172T —NH₂ 15 Q173E Q173E —NH₂ 15 Q173R Q173R —NH₂ 15

FGF21 mutant constructs were prepared using primers having sequencesthat are homologous to regions upstream and downstream of a codon (orcodons) to be mutated. The primers used in such amplification reactionsalso provided approximately 15 nucleotides of overlapping sequence toallow for recircularization of the amplified product, namely the entirevector now having the desired mutant.

An exemplary FGF21 mutant construct, encoding an FGF21 mutant having aglutamic acid residue at position 170 instead of the native glycineresidue (i.e., the G170E mutant) was prepared using the primers shown inTable 12.

TABLE 12 PCR Primers for Preparing Exemplary FGF21 Mutant SEQ ID PrimerSequence NO: Sense 5′-ATGGTGGAACCTTCCCAGGGCCGAAGC-3′ 18 Antisense5′-GGAAGGTTCCACCATGCTCAGAGGGTCCGA-3′ 19

The primers shown in Table 12 allow for the substitution of the glycineresidue with a glutamic acid residue as shown below, wherein the uppersequence is the sense primer (SEQ ID NO: 18), the second and thirdsequences (SEQ ID NOs: 20 and 22) are portions of an FGF21 expressionconstruct, and the fourth sequence is the antisense primer (SEQ ID NO:21):

                5′-ATGGTGG A ACCTTCCCAGGGCCGAAGCCTCCTCGGACCCTCTGAGCATGGTG GGA CCTTCCCAGGGCCGAAGCCCCAGAGGAGCCTGGGAGACTCGTACCAC CCT GGAAGGGTCCCGGCTTCGGGGT    AGCCTGGGAGACTCGTACCACC T TGGAAGG-5′

FGF21 mutant constructs were prepared using essentially the PCRconditions described in Example 1. Amplification products were digestedwith the restriction endonuclease DpnI, and then transformed intocompetent cells. The resulting clones were sequenced to confirm theabsence of polymerase-generated errors. Fc-FGF21 and FGF21-Fc fusionproteins were generated as described herein, e.g., in Example 6.

FGF21 mutants were expressed by transforming competent BL21 (DE3) orBL21 Star (Invitrogen; Carlsbad, Calif.) cells with the constructencoding a particular mutant. Transformants were grown overnight withlimited aeration in TB media supplemented with 40 μg/mL kanamycin, wereaerated the next morning, and after a short recovery period, wereinduced in 0.4 mM IPTG. FGF21 mutant polypeptides were harvested bycentrifugation 18-20 hours after induction.

FGF21 mutants were also analyzed for predicted immunogenicity Immuneresponses against proteins are enhanced by antigen processing andpresentation in the major histocompatability complex (MHC) class IIbinding site. This interaction is required for T cell help in maturationof antibodies that recognize the protein. Since the binding sites of MHCclass II molecules have been characterized, it is possible to predictwhether proteins have specific sequences that can bind to a series ofcommon human alleles. Computer algorithms have been created based onliterature references and MHC class II crystal structures to determinewhether linear amino acid peptide sequences have the potential to breakimmune tolerance. The TEPITOPE computer program was used to determine ifpoint mutations in particular FGF21 mutants would increase antigenspecific T cells in a majority of humans. Based on an analysis of thelinear protein sequence of each FGF21 mutant, none of the mutants waspredicted to enhance immunogenicity.

Example 12 Impact of Linker Sequence on FGF21 Degradation

To determine whether the presence of a longer amino acid linker betweenthe Fc sequence and the FGF21 sequence affects FGF21 degradation, micewere injected with FGF21 fusion proteins in which the Fc region wasseparated from the FGF21 sequence by a 15 amino acid linker having thesequence GGGGGSGGGSGGGGS (SEQ ID NO: 23), blood was withdrawn from themice at various time points, and the serum was analyzed by LC-MS. Inparticular, mice were injected with Fc(15)FGF21 or FGF21(15)Fc (obtainedfrom E. coli) at 23 mg/kg, blood was drawn at 6, 24, and 48 hours, anddrawn blood was affinity purified using an anti-human-Fc agarose resin.

Prior to analyzing the purified samples by LC-MS, Fc(15)FGF21 andFGF21(15)Fc protein standards were analyzed as a reference. Proteinstandards were either reduced with TCEP or not reduced. Both reduced andnon-reduced standards were analyzed by LC-MS using an ACE cyano 0.3mm×30 cm column with the column effluent spraying into an LCQ Classicion-trap mass spectrometer. Since the deconvoluted spectra of thereduced samples were cleaner, the affinity purified samples were reducedprior to LC-MS analysis.

The observed masses for the reduced Fc(15)FGF21 standard andcorresponding affinity purified samples withdrawn at various time pointsare shown in FIGS. 8A-8D. The observed masses for the reducedFGF21(15)Fc standard and corresponding affinity purified sampleswithdrawn at various time points are shown in FIGS. 9A-9D. Some of thestandard and sample eluates were subjected to Edman sequencing in orderto confirm the N-terminus of the proteins and assist in predicting theidentity of the fragments observed by LC-MS. Results of the LC-MSanalysis of the standards and samples and an indication of predictedfragments are provided in Table 13.

TABLE 13 Results of LC-MS Analysis and Predicted Fragments MajorObserved Percent Intact FGF21 Sample Masses of Total FragmentN-terminus? Fc(15)FGF21 46,002 Da 100% 1-424 Yes standard Fc(15)FGF2146,000 Da  65% 1-424 Yes  6 hours 44,978 Da  35% 1-414 Fc(15)FGF2144,978 Da  85% 1-414 Yes 24 hours 43,022 Da  15% 1-394 Fc(15)FGF2144,976 Da  60% 1-414 Yes 48 hours 43,019 Da  40% 1-394 FGF21(15)Fc45,999 Da 100% 1-424 Yes standard FGF21(15)Fc 45,870 Da 100% 1-423 Yes 6 hours FGF21(15)Fc 45,869 Da  40% 1-423 Some 24 hours 45,301 Da  35%6-423 43,460 Da  25% 22-423  FGF21(15)Fc 45,870 Da  15% 1-423 Some 48hours 45,297 Da  20% 6-423 43,461 Da  65% 22-423 

As indicated in Table 13, all of the affinity purified samples showedsome degree of degradation after only 6 hours of circulation. After 24hours of circulation, the major products of Fc(15)FGF21 were fragmentsconsisting of amino acid residues 1-414 (85% of sample) and 1-394 (15%of sample), and the major products of FGF21(15)Fc were fragmentsconsisting of amino acid residues 1-423 (40% of sample), 6-423 (35% ofsample), and 22-423 (25% of sample). Identified cleavage points for theFc(15)FGF21 and FGF21(15)Fc proteins are shown in FIGS. 10A and 10B,respectively.

Example 13 In Vivo Activity of Proteolysis-Resistant Fc(15)FGF21 Mutantsat 1-7 Days after Injection

As described herein, proteolytic cleavage of FGF21 Fc fusion proteinsdepends upon the orientation of the Fc sequence, with the Fc end of thefusion protein being more stable than the FGF21 end of the fusionprotein (i.e., the N-terminal portion of Fc-FGF21 fusion proteins andthe C-terminal portion of FGF21-Fc fusion proteins were found to be morestable). For example, cleavage was identified at positions 5 and 21 ofFGF21-Fc and positions 151 and 171 of Fc-FGF21.

As a result of these observations, an investigation was performed toidentify proteolysis-resistant FGF21 mutants. LC-MS analysis of Fc-FGF21demonstrates that in vivo proteolytic degradation first occurs betweenamino acid residues 171-172, followed by degradation between amino acidresidues 151-152. By blocking proteolytic degradation at position 171,the cleavage at position 151 can be prevented, effectively extending thehalf-life of the molecule. However, proteolysis-resistant mutants inwhich cleavage is prevented at position 151 can still possess residuesat position 171 that are susceptible to protease attack, therebyresulting in a molecule missing the last 10 amino acids, which are knownto be involved in the binding of the co-receptor beta-klotho, which is adeterminant of ligand receptor affinity and in vitro and in vivopotency. Therefore, the mutagenesis of amino acid residues surroundingposition 171 in mature FGF21 appear to be more critical for improvingthe in vivo stability, potency, and efficacy of the molecule.

The in vivo activity of particular proteolysis-resistant Fc(15)FGF21mutants was assayed by intraperitoneally injecting ob/ob mice with anFGF21 mutant, drawing blood samples from injected mice at 0, 0.25, 1, 3,5, and 7 days after injection, and then measuring blood glucose levelsin the samples. The results of one experiment are provided in FIG. 11,which shows the blood glucose levels measured in mice injected with aPBS control, an Fc(15)FGF21 control, or the Fc(15)FGF21 mutantsFc(15)FGF21 G170E, Fc(15)FGF21 P171A, Fc(15)FGF21 S172L, Fc(15)FGF21G170E/P171A/S172L, or Fc(15)FGF21 G151A. FIG. 12 shows the percentchange in blood glucose levels as determined in this experiment. Thisexperiment demonstrates that the Fc(15)FGF21 G170E, Fc(15)FGF21 P171A,Fc(15)FGF21 S172L, and Fc(15)FGF21 G170E/P171A/S172L mutants exhibitsustained blood glucose lowering activity for up to 5 days, which issuperior to the activity of wild-type Fc-FGF21 The Fc(15)FGF21 G151Amutant only partially improved the duration of blood glucose loweringactivity as compared with wild-type Fc-FGF21 fusion protein.Surprisingly, although the Fc(15)-FGF21 S172L mutant is not aproteolysis-resistant mutant, and therefore has similar degradationprofile as the wild-type Fc(15)-FGF21 polypeptide, this mutant was foundto exhibit improved in vivo efficacy as compared with the wild-typeFc(15)-FGF21 polypeptide.

The results of another experiment are provided in FIG. 13, which showsthe blood glucose levels measured in mice injected with a PBS control,an Fc(15)FGF21 control, or the Fc(15)FGF21 mutants Fc(15)FGF21P150A/G151A/I152V, Fc(15)FGF21 G170E, Fc(15)FGF21 G170E/P171A, orFc(15)FGF21 G170E/S172L. FIG. 14 shows the percent change in bloodglucose levels as determined in this experiment. As in the experimentdescribed above, the wild-type Fc-FGF21 fusion protein and theFc(15)FGF21 P150A/G151A/I152V mutant do not exhibit sustained bloodglucose lowering activity, possibly because the degradation at 171 sitecould still occur, and blood glucose levels in animals injected withthese proteins returned to baseline at 24 hours after injection.However, the Fc(15)FGF21 G170E, Fc(15)FGF21 G170E/P171A, or Fc(15)FGF21G170E/S172L exhibit maximal blood glucose lowering activity up to 5 daysafter injection, which is superior to the wild-type Fc-FGF21 fusionprotein and the Fc(15)FGF21 P150A/G151A/I152V mutant.

The results of another experiment are provided in FIG. 15, which showsthe blood glucose levels measured in mice injected with a PBS control orthe Fc(15)FGF21 mutants Fc(15)FGF21 G170E, Fc(15)FGF21 G170A,Fc(15)FGF21 G170C, Fc(15)FGF21 G170D, Fc(15)FGF21 G170N, or Fc(15)FGF21G1705. FIG. 16 shows the percent change in blood glucose levels asdetermined in this experiment. All of the FGF21 mutants tested in thisexperiment exhibited sustained blood glucose lowering activity for up to5 days after injection.

The results of another experiment are provided in FIG. 17, which showsthe blood glucose levels measured in mice injected with PBS or theFc(15)FGF21 mutants Fc(15)FGF21 G170E, Fc(15)FGF21 P171E, Fc(15)FGF21P171H, Fc(15)FGF21 P171Q, Fc(15)FGF21 P171T, or Fc(15)FGF21 P171Y. FIG.18 shows the percent change in blood glucose levels as determined inthis experiment. All of the FGF21 mutants tested in this experimentexhibited improved blood glucose lowering activity when compared withwild-type Fc-FGF21.

Example 14 In Vivo Degradation of Proteolysis-Resistant Fc(15)FGF21Mutants at 6 to 120 Hours after Injection

The in vivo stability of selected FGF21 mutants was analyzed byinjecting mice with an FGF21 mutant, drawing blood from the mice atvarious time points, and analyzing the serum by LC-MS. In particular,mice were injected with either the Fc(15)FGF21 G170E, Fc(15)FGF21 P171A,or Fc(15)FGF21 S172L mutants (obtained from E. coli as described inExample 2), each of which were diluted in approximately 180 μL of 10 mMHCl prior to injection, and blood was drawn at 6, 24, 48, 72, and 120hours. FGF21 proteins were affinity purified from the drawn blood usingan anti-human-Fc agarose resin column. Samples were eluted from thecolumn using 10 mM HCl. All of the FGF21 constructs comprise an Fcregion and 15 amino acid linker at the amino-terminal end of the FGF21protein. Mice were also injected with a wild-type FGF21 control.

Prior to analyzing the affinity purified samples by LC-MS, unprocessedwild-type FGF21 and unprocessed FGF21 mutants were analyzed as areference. All standards and time point samples were reduced with TCEP,and then analyzed by LC-MS using an ACE cyano 0.3 mm×30 cm column withthe column effluent spraying into an LCQ Classic ion-trap massspectrometer. Affinity purified samples were diluted with ammoniumacetate, reduced with TCEP, and then analyzed by LC-MS as describedabove.

The observed masses for wild-type Fc(15)FGF21 at 0, 6, 24, and 48 hoursafter injection are shown in FIGS. 19A-19D, respectively. The observedmasses for Fc(15)FGF21 G170E at 0, 6, 24, and 48 hours after injectionare shown in FIGS. 20A-20D, respectively. The observed masses forFc(15)FGF21 P171A at 0, 6, 24, and 48 hours after injection are shown inFIGS. 21A-21D, respectively. The observed masses for Fc(15)FGF21 S172Lat 0, 6, 24, and 48 hours after injection are shown in FIGS. 22A-22D,respectively.

All of the samples drawn at 72 and 120 hours were found to contain ahigh molecular weight (>200 kDa by non-reducing SDS-PAGE) component offibrinogen that is much more abundant than the remaining Fc(15)FGF21fusion protein. Results of the LC-MS analysis of the other standards andsamples are provided in Table 14.

TABLE 14 Results of LC-MSAnalysis and Predicted Fragments Major ObservedPercent FGF21 Sample Masses of Total Fragment Edman Fc(15)FGF21 WT45,994 Da   100% 1-424 — standard Fc(15)FGF21 WT 46,001 Da    80% 1-424No  6 hours 44,987 Da    20% 1-414 Fc(15)FGF21 WT 44,979 Da ~100% 1-414No 24 hours Fc(15)FGF21 WT 44,980 Da ~100% 1-414 — 48 hours Fc(15)FGF21G170E 46,068 Da   100% 1-424 — standard Fc(15)FGF21 G170E 46,078 Da  100% 1-424 No  6 hours Fc(15)FGF21 G170E 46,074 Da    80% 1-424 No 24hours 45,761 Da    20% 1-421 Fc(15)FGF21 G170E 46,072 Da  ~60% 1-424 No48 hours 45,760 Da  ~40% 1-421 Fc(15)FGF21 P171A 45,970 Da   100% 1-424— standard Fc(15)FGF21 P171A 45,980 Da   100% 1-424 No  6 hoursFc(15)FGF21 P171A 45,973 Da  ~70% 1-424 No 24 hours 45,657 Da  ~30%1-421 Fc(15)FGF21 P171A 45,992 Da  ~50% 1-424 No 48 hours 45,673 Da ~50% 1-421 Fc(15)FGF21 S172L 46,022 Da   100% 1-424 — standardFc(15)FGF21 S172L 46,027 Da   100% 1-424 No  6 hours Fc(15)FGF21 S172L44,984 Da   100% 1-414 No 24 hours Fc(15)FGF21 S172L 44,985 Da   100%1-414 No 48 hours

As indicated in Table 14, the degradation of wild-type Fc(15)FGF21 andthe S172L mutant look similar, in that after 24 hours of circulation,the major product of the fusion protein was a fragment consisting ofamino acid residues 1-414. The degradation products of the Fc(15)FGF21G170E and Fc(15)FGF21 P171A mutants also look similar in that thesamples drawn after 24 hours of circulation contain 70-80% intactprotein (amino acids 1-424) and 20-30% of a fragment consisting of aminoacid residues 1-421. Even after 48 hours, the Fc(15)FGF21 G170E andFc(15)FGF21 P171A mutants still retain intact protein while showing anincrease in the amount of the fragment consisting of amino acid residues1-421. As observed in prior analyses of Fc-FGF21 constructs, degradationof the FGF21 portion of the fusion protein was detected and the Fcportion was found to remain stable. The cleavage sites identified forwild-type, Fc(15)FGF21 G170E, Fc(15)FGF21 P171A, and Fc(15)FGF21 S172Lare shown in FIGS. 23A-23D, respectively.

Example 15 Identification of Aggregation-Reducing FGF21 Mutants

One property of wild-type FGF21 is its propensity to aggregate.Aggregation-reducing FGF21 mutants were identified on the basis of twohypotheses. The first hypothesis is that, with respect to FGF21,aggregation (or dimerization) is triggered by hydrophobic interactionsand van der Waals interactions between FGF21 molecules caused byhydrophobic residues that are exposed to hydrophilic water-based solventenvironment. The second hypothesis is that these exposed hydrophobicresidues can be substituted to create aggregation-reducingpoint-mutation variants without compromising FGF21 activity.

A systematic rational protein engineering approach was used to identifyexposed hydrophobic residues in FGF21. As there were no known X-ray orNMR structures of FGF21 that could be used to identify exposedhydrophobic residues, a high resolution (1.3 Å) X-ray crystal structureof FGF19 (1PWA) obtained from the Protein Databank (PDB) was used tocreate a 3D homology model of FGF21 using MOE (Molecular OperatingEnvironment; Chemical Computing Group; Montreal, Quebec, Canada)modeling software. FGF19 was chosen as a template, since among theproteins deposited in the PDB, FGF19 is the most closely related proteinto FGF21 in terms of the amino acid sequence homology.

Solvent accessibility was calculated by the following method using MOE.A first measure of surface area (SA1) is defined as the area of theresidue's accessible surface in Å². While a particular amino acidresidue appears in a protein's primary sequence multiple times, eachoccurrence of the residue can have a different surface area due todifferences in, inter alia, the residue's proximity to the proteinsurface, the orientation of the residue's side-chain, and the spatialposition of adjacent amino acid residues. Therefore, a second measure ofsurface area (SA2) is made wherein the residue of interest is extractedfrom the protein structure along with that residue's neighboring, oradjacent, residues. These spatially adjacent residues are mutated insilico to glycines to remove their side-chains, and then the SA2 for theresidue of interest is calculated, giving a measure of the totalpossible surface area for that residue in its particular conformation. Aratio of SA1 to SA2 (SA1/SA2) can then give a measure of the percentageof the possible surface area for that residue that is actually exposed.

Several hydrophobic residues that are highly exposed to the solvent wereselected for further analysis, and in silico point mutations were madeto these residues to replace the selected residue with the othernaturally occurring amino acid residues. The changes in protein thermalstability resulting from different substitutions were calculated usingthe FGF21 model and the interactive web-based program CUPSAT (CologneUniversity Protein Stability Analysis Tools) according to instructionsprovided at the CUPSAT website. See Parthiban et al., 2006, NucleicAcids Res. 34: W239-42; Parthiban et al., 2007, BMC Struct. Biol. 7:54.Significantly destabilizing or hydrophobic mutations were excluded inthe design of aggregation-reducing point-mutation variants. Stabilizing(or, in rare cases, slightly destabilizing) substitutions that introduceimproved hydrophilic and/or ionic characteristics were considered ascandidates for aggregation-reducing FGF21 mutants.

A summary of the data generated through this rational proteinengineering approach is provided in Table 15, which also lists exemplaryFGF21 mutants expected to have reduced protein aggregation and improvedstability.

TABLE 15 Calculated Effect of FGF21 Mutants on Stability StabilizationResidue # WT Residue Mutation (Kcal/mol) 26 A K 1.25 E 1.54 R 2.016 45 AT 0.66 Q 0.71 K 1.8 E 2.34 R 1.59 52 L T −0.33 58 L G 0.16 S −0.15 C 1.0E 0.08 60 P A 1.3 K 1.51 E 0.66 R 1.31 78 P A 0.14 C 2.48 R 0.08 H 0.1386 L T 0.18 C 4.1 88 F A 2.52 S 3.08 K 2.88 E 1.48 98 L T 0.49 Q 0.17 K−0.19 C 3.08 E 0.84 R 3.4 99 L C 7.34 E 2.0 D 1.01 R 1.61 111 A T 0.47 K−0.12 129 A Q 3.93 K 1.02 N 3.76 E 3.01 D 3.76 R 1.68 H 2.9 134 A K 5.37Y 4.32 E 5.13 R 6.18 H 2.86

Example 16 Preparation and Expression of Aggregation-Reducing FGF21Mutants and Fusion Proteins

Constructs encoding the FGF21 mutants listed in Table 16 were preparedby PCR amplification of the wild-type FGF21 expression vector asdescribed in Example 11 (the construction of the wild-type FGF21expression vector is described in Example 1). Fusion proteins weregenerated as described herein, e.g., in Example 6.

TABLE 16 Aggregation-reducing FGF21 Mutants Mutation(s) Fc Linker A26EA26K A26R A45E A45K A45K —NH₂ 15 A45R —NH₂ 15 A45Q —NH₂ 15 A45T —NH₂ 15A45K, L98R —NH₂ 15 L52T L58C L58E L58G L58S P60A P60E P60K P60R P78AP78C P78H P78R L86C L86T F88A F88E F88K F88R F88S L98C L98E —NH₂ 15 L98K—NH₂ 15 L98Q —NH₂ 15 L98R L98R —NH₂ 15 L99C L99D L99E L99R A111K —NH₂ 15A111T A129D A129E —NH₂ 15 A129H —NH₂ 15 A129K A129N —NH₂ 15 A129R —NH₂15 A129Q A134E A134H —NH₂ 15 A134K A134Y

The aggregation of various FGF21 proteins, including wild-type FGF21,truncated FGF21 polypeptides, FGF21 mutants, and FGF21 fusion proteinswas assayed by Size Exclusion Chromatography (SEC). Samples to beanalyzed were incubated at 4° C., room temperature, or 37° C. forvarious time points, and then subjected to SEC analysis. Experimentswere performed on a Beckman HPLC system equipped with a SEC column. Forwild-type FGF21, a TOSOHAAS TSK-Gel G2000 SEC column was used with 2×PBScontaining 2% isopropyl alcohol as the mobile phase. For FGF21 Fc fusionproteins and FGF21 mutant polypeptides, a TOSOHAAS TSK-Gel G3000 SECcolumn was used with 2×PBS as the mobile phase.

Example 17 In Vitro Activity of Aggregation-Reducing FGF21 Mutants

Experiments were performed to identify aggregation-reducing mutants thatretain wild-type FGF21 activity in an ELK-luciferase in vitro assay.ELK-luciferase assays were performed as described in Example 4. FIGS.24A-24C show the results of an ELK-luciferase activity assay performedon the FGF21 mutants FGF21 L99R, FGF21 L99D, and FGF21 A111T (FIG. 24A);the FGF21 mutants FGF21 A129D, FGF21 A129Q, and FGF21 A134K (FIG. 24B);and the FGF21 mutants FGF21 A134Y, FGF21 A134E, and FGF21 A129K (FIG.24C). The results of these experiments demonstrate that some of theaggregation-reducing mutations did not adversely impact FGF21 activityas assayed in ELK-luciferase assays.

Example 18 Preparation and Expression of Fc(15)FGF21 Combination MutantsShowing Longer Half-Life and Lower Levels of Aggregation

A number of FGF21 combination mutants, containing mutations shown toreduce aggregation as well as to increase half-life by disruptingproteolytic degradation, were prepared and conjugated to IgG1 Fcmolecules. These FGF21 mutants were prepared essentially as described inExample 11.

Example 19 In Vitro Studies of Fc(15)FGF21 Mutants Showing LongerHalf-Life and Lower Levels of Aggregation

Experiments were performed to identify FGF21 combination mutants thatretain wild-type FGF21 activity in an ELK-luciferase in vitro assay.ELK-luciferase assays were performed as described in Example 4.

FIGS. 25A-25D show the results of an ELK-luciferase activity assayperformed on the Fc-FGF21 mutants Fc-FGF21 P171G, Fc-FGF21 P171S, andFc-FGF21 P171T (FIG. 25A); the Fc-FGF21 mutants Fc-FGF21 P171Y, Fc-FGF21P171W, and Fc-FGF21 P171C (FIG. 25B); Fc(15)FGF21, Fc(15)FGF21A45K/G170E, and FGF21 A45K (FIG. 25C); and Fc(15)FGF21, Fc(15)FGF21P171E, and Fc(15)FGF21 A45K/G170E (FIG. 25D). The results of theseexperiments demonstrate that mutations aimed at improving stability, orboth stability and solubility, did not compromise the in vitro activityas compared with wild-type Fc-FGF21. Interestingly, the FGF21 A45Kmutant showed improved potency relative to wild-type Fc-FGF21.

FIG. 26A shows the change in percent aggregation for an FGF21 control(WT) and FGF21 A45K following incubation of 65 mg/mL protein at 4° C.for 1, 2, and 4 days. The data indicated that the A45K mutation leads toa decrease in aggregation of the protein, compared to the wild-typeprotein.

FIG. 26B shows the change in percent aggregation for an FGF21 control(WT) and FGF21 P78C, P78R, L86T, L86R, L98C, L98R, A111T, A129D, A129Q,A129K, A134K, A134Y, and A134E following incubation of 65 mg/mL proteinat 4° C. for 1, 6, and 10 days. The data indicated that the L86R, L98C,L98R, A111T, A129Q, and A129K lead to a decrease in aggregation of theprotein, compared to the wild-type protein.

FIG. 27 shows the results of an ELK-luciferase activity assay performedon a human FGF21 control and the FGF21 mutants FGF21 A45K, FGF21 L52T,and FGF21 L58E. This experiment demonstrates that the FGF21 A45K mutantretains the full efficacy of wild-type FGF21 and exhibits a potency thatis even greater than wild-type FGF21. However, the FGF21 L52T, and FGF21L58E mutants show reduced potency and efficacy as compared withwild-type FGF21.

FIGS. 28A-28B show the change in aggregation levels for the Fc(15)FGF21mutants Fc(15)FGF21 6-181/G170E, Fc(15)FGF21 A45K/G170E, Fc(15)FGF21P171E, Fc(15)FGF21 P171A, Fc(15)FGF21 G170E, and an FGF21 controlfollowing incubation at 4° C. for 1, 4, and 8 days. This experimentdemonstrates that over the 8 day period, the Fc(15)FGF21 A45K/G170Emutant showed less aggregation than did the Fc(15)FGF21 G170E orFc(15)FGF21 P171E mutants, but all three mutants showed less aggregationthan did the Fc(15)FGF21 control. Table 17 shows the percent aggregationobtained for an Fc-FGF21 control and the Fc-FGF21 A45K/G170E mutantfollowing incubation at 4° C. or room temperature for 0, 2, 3, 4, or 7days.

TABLE 17 Percent Aggregation for Fc-FGF21 and Fc-FGF21 Mutant Sample Day0 Day 2 Day 3 Day 4 Day 7 Fc(15)FGF21 WT 4° C. 1.12 1.71 1.89 2.14 2.3232 mg/mL RT 1.12 6.09 7.94 9.57 12.59 Fc(15)FGF21 A45K/G170E 4° C. 0.450.77 0.88 1.03 1.24 33 mg/mL RT 0.45 3.86 5.22 6.62 8.60

Example 20 Preparation and Expression of Fc-FGF21 Fusion CombinationMutants

As described above, the stability and solubility of FGF21 can bemodulated through the introduction of specific truncations and aminoacid substitutions. In addition, FGF21 stability can be further enhancedby fusing such modified FGF21 proteins with the Fc portion of the humanimmunoglobulin IgG1 gene. Moreover, by introducing combinations of theabove modifications, FGF21 molecules having both enhanced stability andsolubility can be generated. Nucleic acid sequences encoding the FGF21combination mutants listed in Table 18 were prepared using thetechniques described above.

TABLE 18 FGF21 Combination Mutants Amino Acid Proteolysis AggregationResidues Mutation Mutation Fc Linker 1-181 G170E A45K —NH₂ 15 1-181G170E L98R —NH₂ 15 1-181 G170E A45K, L98R —NH₂ 15 1-181 P171G A45K —NH₂15 1-181 P171S A45K —NH₂ 15 1-181 P171G L98R —NH₂ 15 1-181 P171S L98R—NH₂ 15 1-181 P171G A45K, L98R —NH₂ 15 1-178 G170E —NH₂ 15 6-181 G170E—NH₂ 15 6-181 G170E A45K —NH₂ 15 6-181 G170E L98R —NH₂ 15 6-181 P171G—NH₂ 15 6-181 P171G L98R —NH₂ 15 7-181 G170E —NH₂ 15

FIG. 29 shows the blood glucose levels measured in mice injected withthe Fc(15)FGF21 combination mutants Fc(15)FGF21 A45K/G170E, Fc(15)FGF21A45K/P171G, or Fc(15)FGF21 L98R/P171G.

In another experiment the FGF21 mutant Fc(15)FGF21 L98R/P171G wasstudied side-by-side with wild-type mature FGF21 and Fc-FGF21. In oneexperiment, a recombinant 293T cell line was cultured in the presence ofdifferent concentrations of FGF21, Fc-FGF21, or Fc(15)FGF21 L98R/P171Gfor 6 hours. Cell lysates were then assayed for luciferase activity. Asshown in FIG. 30, Fc(15)FGF21 L98R/P171G had similar activity toFc-FGF21, indicating that the introduction of the two point mutationsdidn't alter the molecule's in vitro activity.

In yet another experiment, the stability of the Fc(15)FGF21 L98R/P171Gat 65 mg/mL was evaluated for nine days at two different temperatures,namely room temperature and 4° C., side-by-side with FGF21 and Fc-FGF21.After the incubation period cell lysates were then analyzed withSEC-HPLC to determine an aggregation versus time profile at varioustemperatures. The data shown in FIGS. 31A and 31B indicate that the rateof aggregation formation was significantly reduced in the Fc(15)FGF21L98R/P171G at room temperature (solid triangles, dotted line in FIG.31A) and at 4° C. (solid triangles, dotted line in FIG. 31B).

Example 21 Proteolysis-Resistant FGF21 Mutants Comprising C-TerminalMutations

The in vivo stability of combination mutants was also studied.Specifically, the in vivo stability of Fc(15)FGF21 L98R/P171G wascompared with the stability of Fc(15)FGF21 in murine and cynomolgusmodels. The results were found to be similar in both species. In thecynomolgus study, Fc(15)FGF21 L98R/P171G and Fc(15)FGF21 were injectedIV at 23.5 mg/kg and aliquots of serum and plasma were collected at timepoints out to 840 hours post dose. Time points out to 168 hours wereanalyzed. Time point samples were affinity-purified using anti-Fcreagents, then analyzed using MALDI mass spectrometry. The resultscorrelated well between the two analyses.

Analyzing data generated using immunoaffinity-MALDI, clipping at theP171 site was seen to be eliminated in the Fc(15)FGF21 L98R/P171Gmolecule as a result of the mutation of P171 to P171G. However, a minorand slow degradation resulting in a loss of up to 3 C-terminal residueswas observed for Fc(15)FGF21 L98R/P171G (FIG. 32). The minor cleavagesat the three C-terminal residues were also observed with other FGF21mutants after the more susceptible cleavage site between amino acidresidues 171 and 172 was blocked as shown in FIGS. 20 and 21. The 3C-terminal residue cleavage may represent the cessation of cleavage fromthe C-terminal end of the molecule by a carboxypeptidase in asequential, residue-by-residue fashion or a specific protease attack atamino acid residues 178 and 179 with non-specific clipping at amino acidresidues 179-180 and 180-181. The loss of 2-3 amino acids at theC-terminus could cause reduced beta-klotho binding and ultimatelydecreased potency and in vivo activity of the molecule See, e.g., Yie etal., 2009, FEBS Lett. 583:19-24. To address the apparentcarboxypeptidase degradation of the C-terminus, the impact of adding anamino acid residue “cap” to various FGF21 mutant polypeptides werestudied. A variety of constructs, including those presented in Table 19,were made and assayed using the techniques described herein. Table 19summarizes the results of the in vitro ELK luciferase assay.

Suitable amino acid caps can be between 1 and 15 amino acids in length,for example 1, 2, 3, 4, 5, 10 or 15 amino acids in length. Any numberand type of amino acid(s) can be employed as a cap, for example, asingle proline residue, and single glycine residue, two glycineresidues, five glycine residues, as well as other combinations.Additional examples of caps are provided in the instant Example and inTable 19.

Additionally, to address the apparent protease attack at amino acidresidues 178 and 179, mutation of amino acid residues at positions 179,180 and 181 was studied. Again, a variety of constructs, including thosepresented in Table 19, were made and assayed using the techniquesdescribed herein. The impact of combinations of cap and mutations atthese sites was also explored. Table 19 summarizes exemplary constructsthat were made and studied in the in vitro ELK-luciferase assay, whichwas performed as described herein. Consistent with the terminology usedherein, hFc means a human Fc sequence (i.e., SEQ ID NO:13), L15 refersto a linker having 15 residues (i.e., SEQ ID NO:23)

TABLE 19 Efficacy and EC50 Values for FGF21 Polypeptides ComprisingC-terminal Modifications Constructs Efficacy EC50(nM) huFGF21 0.4 100.0%hFc.L15.hFGF21(L98R, P171G) 2.5  76.1% hFc.L15.hFGF21(L98R, P171G,Y179F) 2.6  78.3% hFc.L15.hFGF21(L98R, P171G, 1-180)hFc.L15.hFGF21(L98R, P171G, 1-179) 7.8  77.4% hFc.L15.hFGF21(L98R,P171G, A180E) 1.9  79.6% hFc.L15.hFGF21(L98R, P171G, S181K) 130  87.9%GSGSGSGSGS.hFGF21.L15.hFc MKEDD.hFGF21.L15.hFc 834  83.1%hFc.L15.hFGF21(L98R, P171G, S181P, P182) 272  69.9% hFc.L15.hFGF21(L98R,P171G, A180G) 3.25  76.9% hFc.L15.hFGF21(L98R, P171G, S181G) 3.43  77.3%hFc.L15.hFGF21(L98R, P171G, L182) hFGF21(L98R, P171G, G182)hFc.L15.hFGF21(L98R, P171G, Y179P) 428  44.4% hFc.L15.hFGF21(L98R,P171G, Y179G) 61  82.6% hFc.L15.hFGF21(L98R, P171G, Y179S) 25.3  74.8%hFc.L15.hFGF21(L98R, P171G, Y179A) 43.2  79.6% hFc.L15.hFGF21(L98R,P171G, S181T) 3.07  77.6% hFc.L15.hFGF21(L98R, P171G, S181A) 2.66  73.5%hFc.L15.hFGF21(L98R, P171G, S181L) 3.46  72.6% hFc.L15.hFGF21(L98R,P171G, S181P) 33.8  79.5% hFc.L15.hFGF21(L98R, P171G, A180P) 617  77.1%hFc.L15.hFGF21(L98R, P171G, A180S) 2.18  84.7% hFGF21(L98R, P171G,GGGGG182-6) hFc.L15.hFGF21(L98R, P171G, P182) 6.1  85.9%hFc.L15.hFGF21(L98R, P171G, G182) 6.5  71.1% hFc.L15.hFGF21(1-178, L98R,P171G) 167  63.9% hFc.L15.hFGF21(L98R, P171G, GG182-3) 1941  84.2%hFc.L15.hFGF21(L98R, P171G, GGGGG182-6) 4307  99.7%

FIG. 33 shows the percent change in blood glucose levels observed indiabetic db/db mice (C57B6 background) injected with a PBS control, wildtype native FGF21, Fc(15)FGF21 (L98R, P171G) and two capped molecules towhich either a proline or glycine residue was added at the C-terminalend, i.e. Fc(15)FGF21 (L98R, P171G, 182P) and Fc(15)FGF21 (L98R, P171G,182G). In the instant Example, when a residue was added to theC-terminus of a wild-type or mutant FGF21 polypeptide, the residue isreferred to by its position in the resultant protein. Thus, “182G”indicates that a glycine residue was added to the C-terminus of themature 181 residue wild-type or mutant protein. FIG. 33 shows thatnative FGF21 lowered blood glucose levels for 6 hours while all threeFc(15)FGF21 mutants studied showed sustained blood glucose-loweringactivity for at least 120 hours. Fc(15)FGF21 (L98R, P171G, 182P),molecule comprising the addition of a proline residue at the C-terminusof the FGF21 component of the fusion molecule, appeared most potent andresulted in lowest blood glucose levels compared with Fc(15)FGF21 (L98R,P171G) and Fc(15)FGF21 (L98R, P171G, 182 G).

In a subsequent experiment, the in vivo activity of (L98R, P171G, 182G)and Fc(15)FGF21 (L98R, P171G, 182P) was studied and compared to the invivo activity of a capped molecule comprising a two glycine addition atthe C-terminus, namely Fc(15)FGF21 (L98R, P171G, 182G 183G). FIG. 34shows the results of that experiment. FIG. 34 shows the percent changein blood glucose levels observed in ob/ob mice injected with PBScontrol, Fc(15)FGF21 (L98R, P171G), Fc(15)FGF21 (L98R, P171G, 182G183G), Fc(15)FGF21 (L98R, P171G, 182G) and Fc(15)FGF21 (L98R, P171G,182P).

As shown in FIG. 34, all of the molecules studied showed sustainedglucose-lowering activity compared with the PBS control. This experimentconfirmed the previous results (FIG. 33) that Fc(15)FGF21 (L98R, P171G,182P) with a proline addition at the C-terminus showed slightly enhancedglucose-lowering efficacy compared with the molecule without a prolinecap, e.g. Fc(15)FGF21 (L98R, P171G). However, the addition of twoglycine residues at the C-terminus, e.g. Fc(15)FGF21 (L98R, P171G, 182G183G), appeared to reduce the molecule's in vivo potency and shortenedthe duration of in vivo glucose-lowering effect.

FIG. 35 shows the percent change in blood glucose levels observed indiabetic db/db mice (C57B6 background) injected with PBS control or theFGF21 mutant polypeptides Fc(15)FGF21 (L98R, P171G), Fc(15)FGF21 (L98R,P171G, Y179S), Fc(15)FGF21 (L98R, P171G, Y179A), Fc(15)FGF21 (L98R,P171G, A180S), and Fc(15)FGF21 (L98R, P171G, A180G). All mutants showedsimilar glucose-lowering activity with similar duration of action.

FIG. 36 shows the percent change in blood glucose levels observed indiabetic db/db mice (C57B6 background) injected with vehicle control,Fc(15)FGF21 (L98R, P171G), Fc-FGF21 (L98R, P171G, Y179F), andFc(15)FGF21 (L98R, P171G, A180E). Compared with Fc(15)FGF21 (L98R,P171G), Fc(15)FGF21 (L98R, P171G, Y179F) was less efficacious inlowering blood glucose. However, Fc(15)FGF21 (L98R, P171G, A180E), inwhich alanine at amino acid position of 180 was mutated to glutamicacid, was more efficacious than Fc(15)FGF21 (L98R, P171G) and causedadditional 20% reduction of blood glucose levels compared withFc(15)FGF21 (L98R, P171G). These data suggest that A180E mutation mayhave reduced the C-terminal degradation in vivo and thereby improved invivo potency and efficacy of the molecule.

Example 22 Rhesus Monkey Study

An Fc-Linker-FGF21 construct was generated using methodology describedherein. The construct comprised an IgG1 Fc sequence (SEQ ID NO:13) fusedat the C-terminus to a (Gly)₅-Ser-(Gly)₃-Ser-(Gly)₄-Ser linker sequence(SEQ ID NO:23) which was then fused at the C-terminus to the N terminusof a mature FGF21 sequence (SEQ ID NO:4), into which two mutations, L98Rand P171G, had been introduced. This construct was then expressed andpurified as described herein, and was isolated as a dimeric form of theprotein, each monomer of which was linked via intermolecular disulfidebonds between the Fc region of each monomer. This molecule is referredto in the instant Example as “Fc-FGF21(RG)” and has the amino acidsequence of SEQ ID NO: 38 and is encoded by SEQ ID NO:37. In thisExample, FGF21 refers to the mature form of FGF21, namely SEQ ID NO:4.

22.1 Study Design

The Fc-FGF21(RG) construct was administered chronically andsubcutaneously (“SC”) into non-diabetic male Rhesus monkeys with aBMI>35. Two other groups of monkeys (n=10 per group) were treated witheither mature FGF21 (i.e., SEQ ID NO:4) or a vehicle control.

Animals were acclimated for 42 days prior to administration of any testcompound and were then divided into groups of 10 and administeredmultiple SC injections of test compounds or control article in a blindedfashion, as depicted graphically in FIG. 37. In brief, each animal wasinjected once a day with compound or vehicle. FGF21 was administereddaily, whereas Fc-FGF21(RG) was administered weekly. Fc-FGF21(RG) andFGF21 doses were escalated every 2 weeks, as shown in FIG. 37. Bodyweight and food intake were monitored throughout the study. The CRO wasblinded to the treatment.

Two oral glucose tolerance tests (OGTTs) were performed prior to thestart of the treatment. OGTT1 was used to sort the animals into threeequivalent groups having a similar distribution of animals based on areaunder the curve (AUC) and body weight. The results of the second OGTT(OGTT2) was used to confirm the sorting of the first OGTT (OGTT1).Monkeys with OGTT profiles that were inconsistent from one test (OGTT1)to the next (OGTT2) were excluded. The results of OGTTs 1 and 2 areshown in FIGS. 38A and 38B, with AUC measurements shown in FIG. 38C.Baseline body weight is shown in FIG. 38D and Table 20.

OGTTs 3, 4, and 5 were performed every 2 weeks at the end of each dosetreatment of low, mid and high doses. Blood samples were collected fromfasted animals weekly and were used to measure glucose, insulin,triglyceride levels, as well as the levels of test compound. Bloodsamples were also collected weekly during the 3-week washout period.

Baseline OGTT1 and OGTT2 showed an expected glucose profile as seen innormal animals, with a maximum plasma glucose obtained at 30 minutes,and demonstrated stable AUCs for the 3 different groups.

Fasting baselines values for plasma chemistry are shown in Table 20.Plasma chemistry measurements were performed on blood samples collectedprior to the start of the treatment.

TABLE 20 Baseline Values for Body Weight, Fasting Plasma Glucose,Insulin, and Triglyceride Levels of the Three Groups of Rhesus MonkeysVehicle FGF21 Fc-FG21(RG) N 10 10 10 Body weight (kg) 8.5 ± 0.5 8.7 ±0.4 8.5 ± 0.4 Plasma glucose 91.9 ± 4.8  94.8 ± 5.3  82.2 ± 3.7  (mg/dL)Insulin (pg/mL) 942.6 ± 121.4 976.1 ± 107.7 1023.4 ± 205.1 Triglycerides (mg/dL) 44.4 ± 4.8  58.6 ± 5.2  71.7 ± 9.8 

Three different dose levels were selected, the low dose was 0.1 and 0.3mg/kg, the mid dose was 0.3 and 1 mg/kg and the high dose was 1 and 5mg/kg for FGF21 and Fc-FGF21(RG), respectively. Dose levels were chosenbased on the observed dose-response in mice, with a dosing regimen basedon the anticipated frequency of injection in humans. Equimolar doses ofFGF21 were used for the low and mid doses, and the Fc-FGF21(RG) highdose was raised to 5 mg/kg (i.e., instead of 3 mg/kg, which would havebeen equimolar to the 1 mg/kg FGF21 dose).

22.2 Effect of Test Compounds on Body Weight

In this experiment, in order to measure effect of the test compounds onbody weight measured weekly, the percent body weight change frombaseline was calculated weekly in the three different groups of Rhesusmonkeys. Body weight was also measured during the three week of wash outperiod. Baseline body weight values for each group are included in Table20.

Body weight was followed throughout the study, both pre- andpost-administration of test compounds. Body weight percent change frombaseline of the vehicle animals increased with time, whereas body weightof animals treated with Fc-FGF21(RG) and FGF21 decreased in adose-dependent fashion over the course of the 6 week treatment period,as shown in FIG. 39. As observed previously in rodents (Xu et al.,Diabetes 58(1):250-9 (2009)), treatment with FGF21 statisticallysignificantly decreased body weight. Fc-FGF21(RG) had a greater exposurethan did FGF21 (FIG. 48 and FIG. 47, respectively), offering a possibleexplanation for the observation that Fc-FGF21(RG) showed a morepronounced body weight decrease than FGF21.

22.3. Effect of Test Compounds on Insulin Levels

Insulin levels were measured in blood samples that had been collectedafter an overnight fast or after an afternoon meal.

Fasting plasma insulin levels were measured in Rhesus monkeys every weekin animals treated with either vehicle, FGF21 or Fc-FGF21(RG) and duringthe 3-week washout period. Fasted blood samples were drawn approximatelyfive days after the last Fc-FGF21(RG) injection and approximately 21hours after the last FGF21 injection.

Fed plasma insulin levels were measured in Rhesus monkeys during thefifth and sixth week of treatment with either vehicle or FGF21 duringthe high dose treatment. Fed blood samples were drawn approximatelythree days after Fc-FGF21(RG) injection and approximately 2 hours afterlast FGF21 injection. FIG. 40 shows the effect of vehicle, FGF21 andFc-FGF21(RG) on fasted insulin levels over the full nine week study,while FIG. 41 depicts fed insulin levels determined from samples takenduring weeks 5 and 6.

Summarily, at the two highest doses, both FGF21 and Fc-FGF21(RG)statistically significantly decreased fasted and fed plasma insulinlevels. The observation that insulin levels of animals treated withFGF21 and Fc-FGF21(RG) were decreased without observing increasedglucose levels is indicative of increased insulin sensitivity.

22.4 Effect of Test Compounds on OGTT (Glucose and Insulin)

Three OGTTs (OGTTs 3, 4 and 5) were performed after treatment wasinitiated. OGTT5 glucose and insulin level profiles were measured inanimals treated for 6 weeks with vehicle, FGF21 or Fc-FGF21(RG),corresponding to the last two weeks of the high dose escalation regimen.OGTT5 was conducted approximately 7 days after the last Fc-FGF21(RG)injection, and approximately 21 hours after the last FGF21 injection.The OGTT5 glucose and insulin profiles are shown in FIG. 42 and FIG. 43,respectively. Animals treated with Fc-FGF21(RG) showed an improvedglucose clearance compared to vehicle-treated animals only at thehighest dose and at the last time point measured, as shown in FIG. 42.At the end of the last dose, Fc-FGF21(RG) showed the strongestimprovement in glucose clearance. FGF21 showed no improvement in glucoseclearance. Fc-FGF21(RG) had a greater exposure than did FGF21 (FIG. 48and FIG. 47, respectively), offering a possible explanation for theobservation that Fc-FGF21(RG) showed a more pronounced effect in glucoseclearance than FGF21. Insulin levels during OGTT5 were statisticallysignificantly lowered at the last time point measured in animals treatedwith Fc-FGF21(RG) compared to animals treated with vehicle.

Glucose AUC percent change from baseline was calculated for the threeOGTT (OGTTs 3, 4 and 5) performed at the end of each of the low, mid andhigh doses in the three groups different groups of Rhesus monkeys asshown in FIG. 44. OGTT5 was conducted approximately seven days after thelast Fc-FGF21(RG) injection and 21 hours after last FGF21 injection andshowed that Fc-FGF21(RG) statistically significantly reduced AUC5.Baseline OGTT values for each group are shown on FIG. 38C.

Fasted plasma glucose levels were measured on days when no OGTTs wereperformed. There were no meaningful statistical differences observed infasted plasma glucose levels measured among the three groups of animals.

22.5 Effect of Test Compounds on Triglyceride Levels

Percent change of fasting plasma triglyceride levels was calculated inRhesus monkeys every week in animals treated with either vehicle, FGF21or Fc-FGF21(RG) and during the 3-week washout period. Fasted bloodsamples were drawn approximately five days after last Fc-FGF21(RG)injection and approximately 21 hours after last FGF21 injection.Triglyceride levels were measured every week after the treatment wasinitiated and percent changes from baseline are shown in FIG. 45,fasting baseline values are shown in Table 20.

As depicted in FIG. 45, animals treated with either Fc-FGF21(RG) orFGF21 showed a dose-dependent decrease in triglyceride levels, withFc-FGF21(RG) having the greatest lowering effect compared to FGF21.

FIG. 46 shows the plasma triglyceride levels in samples acquire fromRhesus monkeys in a fed state, during the fifth and sixth week oftreatment with vehicle or Fc-FGF21(RG) or FGF21. Fed blood samples weredrawn approximately 3 days after Fc-FGF21(RG) injection andapproximately 2 hours after last FGF21 injection. Fed plasmatriglyceride levels of animals treated with FGF21 and Fc-FGF21(RG) werestatistically significantly reduced, compared to the triglyceride levelsof animals treated with vehicle (FIG. 46).

22.6 Concentration of Test Compounds

The exposure of the tested compounds administered at approximatelyequivalent molar dose levels was assessed throughout the study period.The concentration of Fc-FGF21(RG) was measured at pre-dose, andapproximately 5 days after the last injection. FGF21 levels weremeasured at pre-dose, and at 5, 12, 19, and 26 days. Blood samples weredrawn at approximately 21 hours after the last injection.

The individual concentration of the tested compounds in each monkeys areshown in FIGS. 47 and 48. As shown in FIG. 47, the majority of theanimals in the FGF21-treated group had concentrations below thequantitation limit. FIG. 48 shows that animals in theFc-FGF21(RG)-treated group had detectable levels of Fc-FGF21(RG) duringeach dosing phase (two weekly doses at the same dose strength). Theaverage concentration from each dosing phase increased approximatelydose-proportionally from 0.3 to 5 mg/kg for Fc-FGF21(RG). There isminimal accumulation as demonstrated by the steady concentrations afterthe first and second weekly dose within each dose escalation phase forboth compounds. During the treatment-free phase (washout period)Fc-FGF21(RG) levels were detectable up to approximately day 47 (12 dayspost last dose) and were below lower limit of quantification (LLOQ)afterwards.

Exposure of the test compounds was also monitored during each OGTT.FGF21 was not detectable during OGTTs 3 and 4, following low- andmid-dose FGF21 treatment. However, measurable levels were observedduring OGTT5, following high-dose treatment. A dose proportionalincrease in Fc-FGF21(RG) levels was observed across the third to fifthOGTT with escalating dose levels, as shown in FIG. 49.

Compound levels data confirm that the animals were exposed to theexpected amount of each compound, namely FGF21 and Fc-FGF21(RG), in adose escalation manner. A large variability was observed in the amountof FGF21 measured, which was an expected result considering the samplingwas performed approximately 21 hours post the last dose and the halflife of FGF21 is approximately 1 hour.

22.7 Conclusions

FGF21 decreased fasted and fed plasma triglyceride and insulin levelsand decreased body weight at the highest doses. Fc-FGF21(RG) improvedOGTT and decreased insulin levels at the highest dose, and dosedependently decreased fasted and fed plasma triglyceride levels as wellas body weight. Both FGF21 and Fc-FGF21(RG) decreased a number ofmetabolic parameters in the non diabetic Rhesus monkeys. Insulin andtriglyceride level decreases were identical between FGF21 andFc-FGF21(RG) when circulating compound levels were in a similar range,in the fed condition. Due to its improved properties, Fc-FGF21(RG) wassuperior to FGF21 in most of the parameters measured and could beadministered once-a-week to observe efficacy on metabolic parameters.

While the present invention has been described in terms of variousembodiments, it is understood that variations and modifications willoccur to those skilled in the art. Therefore, it is intended that theappended claims cover all such equivalent variations that come withinthe scope of the invention as claimed. In addition, the section headingsused herein are for organizational purposes only and are not to beconstrued as limiting the subject matter described.

All references cited in this application are expressly incorporated byreference herein.

What is claimed is:
 1. An isolated fusion protein comprising: (a) an IgGconstant domain; (b) a linker sequence fused to the IgG constant domain;and (c) an FGF21 mutant fused to the linker sequence and wherein theFGF21 mutant comprises the amino acid sequence of SEQ ID NO: 4, whereinan arginine residue has been substituted for the leucine residue atposition 98, and wherein a glutamic acid residue has been substitutedfor the glycine at position
 170. 2. The isolated fusion protein of claim1, further comprising (i) an N-terminal truncation of 8 or fewerresidues; (ii) a C terminal truncation of 12 or fewer residues; or (iii)an N-terminal truncation of 8 or fewer residues and a C terminaltruncation of 12 or fewer residues.
 3. The isolated fusion protein ofclaim 2, wherein the polypeptide is capable of lowering blood glucose ina mammal.
 4. The isolated fusion protein of claim 1, wherein thepolypeptide is covalently linked to one or more polymers.
 5. Theisolated fusion protein of claim 4, wherein the polymer is PEG.
 6. Apharmaceutical composition comprising the isolated fusion protein ofclaim 1 and a pharmaceutically acceptable formulation agent.
 7. A methodselected from the group consisting of reducing triglyceride levels in apatient, improving glucose tolerance in a patient, lowering body weightin a patient, and lowering insulin levels in a patient, said methodcomprising administering to a human patient in need thereof thepharmaceutical composition of claim
 6. 8. The method of claim 7, whereinsaid patient has diabetes.
 9. The method of claim 7, wherein saidpatient is obese.
 10. The isolated fusion protein of claim 1, furthercomprising a lysine residue substituted for the alanine at position 45.11. The isolated fusion protein of claim 10, further comprising (i) anN-terminal truncation of 8 or fewer residues; (ii) a C terminaltruncation of 12 or fewer residues; or (iii) an N-terminal truncation of8 or fewer residues and a C terminal truncation of 12 or fewer residues.12. The isolated fusion protein of claim 11, wherein the polypeptide iscapable of lowering blood glucose in a mammal.
 13. The isolated fusionprotein of claim 10, wherein the polypeptide is covalently linked to oneor more polymers.
 14. The isolated fusion protein of claim 13, whereinthe polymer is PEG.
 15. A pharmaceutical composition comprising theisolated fusion protein of claim 10 and a pharmaceutically acceptableformulation agent.
 16. A method selected from the group consisting ofreducing triglyceride levels in a patient, improving glucose tolerancein a patient, lowering body weight in a patient, and lowering insulinlevels in a patient, said method comprising administering to a humanpatient in need thereof the pharmaceutical composition of claim
 15. 17.The method of claim 16, wherein said patient has diabetes.
 18. Themethod of claim 16, wherein said patient is obese.
 19. An isolatednucleic acid encoding a fusion protein comprising: (a) an IgG constantdomain; (b) a linker sequence fused to the IgG constant domain; and (c)an FGF21 mutant fused to the linker sequence and wherein the FGF21mutant comprises the amino acid sequence of SEQ ID NO: 4, wherein anarginine residue has been substituted for the leucine residue atposition 98, and wherein a glutamic acid residue has been substitutedfor the glycine at position
 170. 20. A vector comprising the nucleicacid molecule claim
 19. 21. A host cell comprising the nucleic acidmolecule of claim 19.